\ ˈbās How to pronounce base (audio) \
plural bases\ ˈbā-​səz How to pronounce bases (audio) \

Definition of base

 (Entry 1 of 4)

1a : the bottom of something considered as its support : foundation the base of the mountain the lamp's heavy base
b biology : that part of a bodily organ by which it is attached to another more central structure of the organism the base of the thumb

c architecture

(1) : the lower part of a wall, pier, or column considered as a separate architectural feature
(2) : the lower part of a complete architectural design (as of a monument)

d mathematics

(1) : a side or face (see face entry 1 sense 5a(5)) of a geometrical figure from which an altitude (see altitude sense 1c(1)) can be constructed especially : a side or face on which the figure stands the base of a triangle
(2) : the length of a base determining the triangle's base
2a : a main ingredient paint having a latex base
b : a supporting or carrying ingredient (as of a medicine)
c : a first or bottom layer of something on which other elements are added Overnight, Utah's famous snow has freshly blanketed both runs, adding to a solid base of three feet …— Abby Carroll
3a : the fundamental part of something : groundwork, basis the book's theoretical base her broad base of knowledge
b : something (as a group of people) that reliably provides support (such as for a business or political candidate) usually singular efforts to expand their customer basethe band's fan baseBut I do believe that that's a very sore point with many Democrats and could be used to energize their base.— John McCain
c Marxism : the economic factors on which all legal, social, and political relations are formed
4a : the starting point or line for an action or undertaking plans to make this city his base of operation— J. A. Loftus
b : a baseline in surveying
c : a center or area of operations The company has its base in London. : such as
(1) : a permanent military installation a naval base The troops were ordered back to base.
(2) : the place from which a military force draws supplies
(3) : a place where military operations begin
d linguistics : root sense 6 "Leave" is the base of the verb "left."

e mathematics

(1) : a number (such as 5 in 56.44 or 57) that is raised to a power (see power entry 1 sense 5a) especially : the number that when raised to a power equal to the logarithm of a number yields the number itself The logarithm of 100 to the base 10 is 2 since 102 = 100.
(2) : a number equal to the number of units in a given digit's place (see place entry 1 sense 8) that for a given system of writing numbers is required to give the numeral 1 in the next higher place The decimal system uses a base of 10. also : such a system of writing numbers using an indicated base Convert from base 10 to base 2.
(3) : a number that is multiplied by a rate or of which a percentage or fraction is calculated To find the interest on $90 at 10 percent multiply the base 90 by .10.
5a : any one of the four stations at the corners of a baseball or softball infield allowing the batter to reach base
b in various games : the starting place or goal
c : a point to be considered His opening remarks touched every base.

6 chemistry

a : any of various typically water-soluble and bitter tasting compounds that in solution have a pH greater than 7, are capable of reacting with an acid to form a salt, and are molecules or ions able to take up a proton from an acid or able to give up an unshared pair of electrons to an acid
b : any of the five purine or pyrimidine bases of DNA and RNA that include cytosine, guanine, adenine, thymine, and uracil
7 finance : a price level at which a security (see security sense 3) previously declining in price resists further decline
8 heraldry : the lower part of a heraldic field (see field entry 1 sense 3c)
9 linguistics : the part of a transformational grammar that consists of rules and a lexicon and generates the deep structures of a language
10 : an electrode that modulates the current flowing through a bipolar junction transistor according to the voltage applied to the electrode This gate, which is called a grid in a tube and a base in a transistor, enables a small "controlling" voltage to turn on and off a much larger voltage between the cathode and the anode.— Thom Hartmann — compare gate entry 1 sense 5b
cover all the bases or less commonly cover every base or have (all) one's bases covered
: to do or include everything that needs to be done or included : to fulfill all requirements or necessities The well rounded menu covers all the bases—pork or duck breast and always a grilled chicken with complementary sauces and relishes …— Caroline Bates In other words, we need to cover every base. Too often, something is remembered at the last minute and we find ourselves waiting for the stores to open on sale day so we can purchase a much-needed item.— Sue Story In your e-mail, let the company know that, for their convenience, you're e-mailing the resume and letter, but that the original documents will arrive by postal service. This way you've got all your bases covered.— Peter Post
off base
1 : wrong, mistaken Estimates were way off base.
2 : unawares caught off base by the charges
touch all the bases or less commonly touch every base
1 : to mention every subject that needs to be considered a speech that touches all the bases
2 : to do or include everything that needs to be done or included : to fulfill all requirements or necessities need to touch all the bases when applying for a mortgage The owner of the Utah Stars is in Salt Lake City, working 24 hours a day in an effort to touch every base to keep his club in Utah's capital city.— Dan Pattison


based; basing

Definition of base (Entry 2 of 4)

transitive verb

1 : to find a foundation or basis for : to find a base (see base entry 1 sense 3a) for usually used with on or upon base an opinion on faulty informationa story based upon real-life events
2 : to make, form, or serve as a base for … great roots based the tree columns …— George Macdonald the company is based in London clients who are based out of their homes


adjective (1)

Definition of base (Entry 3 of 4)

1a : lacking or indicating the lack of higher qualities of mind or spirit : ignoble seemed a base betrayal of idealism— L. M. Sears appealing to a person's baser instincts
b : lacking higher values : degrading a drab base way of life
2a : being of comparatively low value and having relatively inferior properties (such as lack of resistance to corrosion) a base metal such as iron — compare noble entry 1
b : containing a larger than usual proportion of base metals base silver denarii

3 feudalism

a : resembling a villein : servile a base tenant
b : held by villenage base tenure
4 archaic : of little height … the cedar stoops not to the base shrub's foot …— Shakespeare
5 archaic : baseborn base in kind and born to be a slave.— William Cowper
6 obsolete : low in place or position … fall to the base earth from the firmament!— Shakespeare
7 obsolete : bass


adjective (2)

Definition of base (Entry 4 of 4)

1 : constituting or serving as a base This situation is frequently encountered by seaplane pilots in northern Canada who must fly over lakes and tundra to a base camp located on a river.— Alan Lopez
2 : of the simplest or most basic design or form : having the form of something before upgrades or customization This GTO's 350-hp, 5.7-liter V8 is the same that's used in the base Corvette, and it produces the power and throaty exhaust sound of a classic muscle car.Consumer Reports

Illustration of base

Illustration of base


base of a column: 1 upper torus, 2 scotia, 3 lower torus, 4 plinth, 5 shaft, 6 fillets

In the meaning defined above

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Other Words from base


baseless \ ˈbā-​sləs How to pronounce baseless (audio) \ adjective

Adjective (1)

basely adverb
baseness noun

Choose the Right Synonym for base

Adjective (1)

base, low, vile mean deserving of contempt because of the absence of higher values. base stresses the ignoble and may suggest cruelty, treachery, greed, or grossness. base motives low may connote crafty cunning, vulgarity, or immorality and regularly implies an outraging of one's sense of decency or propriety. refused to listen to such low talk vile, the strongest of these words, tends to suggest disgusting depravity or filth. a vile remark

Examples of base in a Sentence


the firm belief that complete trust between husband and wife is the base of any successful marriage the army's base of attack was kept top secret until the battle began


They are going to base their new company in Seattle. The company has based itself in London. Our tour group based itself in a hotel in the heart of the city.

Adjective (1)

Iron is a base metal. a base and sneaky act that is a clear violation of international law
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Recent Examples on the Web: Noun

But what about Matt Olson, with 29 homers, great defense, has reached base 16 games in a row? Scott Ostler,, "A’s threatening to cross line between irritant and nightmare," 8 Sep. 2019 Hours after the second explosion, the Taliban set off a car bomb outside an Afghan military base, killing four civilians. Fox News, "Trump scraps secret meetings with Afghan, Taliban leaders after deadly bombing," 8 Sep. 2019 Then Zobrist reached base five times in the series-opening win, providing at least a temporary solution to the seasonlong black hole in the leadoff spot and bringing a sense of normalcy to this season. Paul Sullivan,, "Column: Javier Baez’s thumb injury puts the onus on the rest of the Cubs to deliver down the stretch," 7 Sep. 2019 Kodiak is home to the nation’s largest Coast Guard base, and each summer brings a wave of transfers. James Brooks, Anchorage Daily News, "Alaska’s coastal communities prepare for big change as ferry cuts arrive this week," 5 Sep. 2019 Carbonite employs 1,600 people globally, including about 280 at its Boston headquarters, but its largest operation is now in Broomfield (Webroot’s home base), where about 380 people work., "Carbonite putting together new leadership team in the absence of a CEO," 5 Sep. 2019 Choose a nice oval pumpkin with a wide base for stability, then follow the pattern to carve out feathers, beak, and eyes. Woman's Day Staff, Woman's Day, "Whoo Is the Wisest? Pumpkin," 5 Sep. 2019 The Democratic base, tired of half-wins and emboldened by 2018, is coming for him. Nic Garcia, The Denver Post, "5 storylines to watch in Colorado politics: TABOR, the 8th Congressional District and more," 5 Sep. 2019 Mr Trump did not disclose which of six shortlisted bases across three states—Alabama, California and Colorado—would accommodate Space Command.. The Economist, "Donald Trump unveils Space Command," 5 Sep. 2019

Recent Examples on the Web: Verb

Kramer said those prices were in line with other municipal courses, based on conversations with golf pros. Darcy Costello, The Courier-Journal, "Dueling proposals in Metro Council could shape the future of city-owned golf courses," 10 Sep. 2019 That’s why La Jolla Music Society President Ted DeDee and his fiancée Pamela Hinchman, a Northwestern University music professor, set their wedding date based on Ginsburg’s travel schedule. San Diego Union-Tribune, "Column: Supreme Court’s Ruth Bader Ginsburg officiates at La Jolla music executive’s wedding," 9 Sep. 2019 The Trump administration got the Taliban to the negotiating table, Mr. Cunningham said, in part by erasing a timeline for withdrawing troops, and instead basing it on security conditions. Lara Jakes, New York Times, "Trump Declares Afghan Peace Talks With Taliban ‘Dead’," 9 Sep. 2019 The agenda was based on 150 interviews conducted across Europe, asking people which issues mattered most to them. R.d. | Paide, The Economist, "Why democracy festivals, a staple in northern Europe, are spreading," 9 Sep. 2019 Unsurprisingly, Lifetime's take on the scandal revolves around two moms who may or may not (but almost certainly are) based on the actresses. Kayleigh Roberts, Marie Claire, "Lifetime Releases Trailer for Its 'College Admissions Scandal' TV Movie," 7 Sep. 2019 The stated range is 99 miles on a full charge, which will vary based on ride mode, terrain, speed, temperature, and load weight. Arv Voss, Houston Chronicle, "BMW C evolution: Maxi-scooter with non-liquid juice," 7 Sep. 2019 Lots of them provide fanciful concepts, some even creating their own drawings of what new iPhones could look like based on reports, and some are even trustworthy. Courtney Linder, Popular Mechanics, "Everything We Know Apple's Upcoming iPhone Event," 6 Sep. 2019 North Carolina Republicans said that the maps discriminated based on partisanship but not race. David Daley, The New Yorker, "The Secret Files of the Master of Modern Republican Gerrymandering," 6 Sep. 2019

Recent Examples on the Web: Adjective

He is set to earn a base salary of $2.025 million this season. John Reid,, "Jaguars’ Yannick Ngakoue motivated to have big season despite no contract extension," 3 Sep. 2019 Women players under contract earn a base salary of $100,000 and can earn some bonuses based on game performance. Time, "Philadelphia Standoff Suspect Charged With Attempted Murder," 16 Aug. 2019 According to the Chronicle of Higher Education’s 2017 survey, which was based on 2016 pay, the University of Texas system’s Chancellor William McRaven took the number 2 spot, with a base salary of $1.2 million and a $300,000 bonus. Rachel Leingang, azcentral, "Michael Crow, other university presidents get salary increases," 31 May 2018 Dickson hasn’t played at all during the preseason following knee surgery, and his salary ($3.3 million base salary) could factor into the final decision., "Seattle Seahawks’ 53-man roster projection for the 2019 season," 28 Aug. 2019 But the team is also required to pay the player his base salary — which in Thomas’s case equals $423,529 for six weeks, and an additional $70,588 for every week thereafter. Ben Volin,, "Cocaine charge shouldn’t affect Patrick Chung’s season, and other Patriots thoughts," 26 Aug. 2019 Signed to a four-year, $26 million contract and due a nonguaranteed $5.5 million base salary, Miller is entering the final year of his deal. Aaron Wilson, Houston Chronicle, "Texans' Lamar Miller out for season with torn ACL and MCL," 25 Aug. 2019 Under the new contract, new firefighters would start this year at a base salary of $53,560, with an increase through each of five years up to $79,286, and beyond that for drivers and higher ranks. Thomas Jewell,, "With city income tax collections stable, Shaker OKs fire contract, non-union COLA," 20 Aug. 2019 Ecarma's current contract was set to expire June 30, 2023 and paid him a base salary of $150,000. Danielle Lerner, The Courier-Journal, "Louisville fires veteran men's tennis coach Rex Ecarma after independent investigation," 16 Aug. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'base.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of base


14th century, in the meaning defined at sense 1c(1)


1587, in the meaning defined at sense 2

Adjective (1)

14th century, in the meaning defined at sense 4

Adjective (2)

1734, in the meaning defined at sense 1

History and Etymology for base


Middle English, from Anglo-French, from Latin basis, from Greek, step, base, from bainein to go — more at come


verbal derivative of base entry 1

Adjective (1)

Middle English bas, from Anglo-French, from Late Latin bassus fat, short, low

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Statistics for base

Last Updated

17 Sep 2019

Look-up Popularity

Time Traveler for base

The first known use of base was in the 14th century

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More Definitions for base



English Language Learners Definition of base

 (Entry 1 of 2)

: the bottom or lowest part of something : the part on which something rests or is supported
: something (such as a group of people or things) that provides support for a place, business, etc.
: a main ingredient to which other things are added to make something



English Language Learners Definition of base (Entry 2 of 2)

: to have a particular place as the main place where a person works or lives or where a business operates


\ ˈbās How to pronounce base (audio) \

Kids Definition of base

 (Entry 1 of 3)

1 : a thing or a part on which something rests : bottom, foundation the base of a statue the base of the mountain
2 : a starting place or goal in various games
3 : any of the four stations a runner in baseball must touch in order to score
4 : the main place or starting place of an action or operation The company's base is in New York.
5 : a place where a military force keeps its supplies or from which it starts its operations an air force base
6 : a line or surface of a geometric figure upon which an altitude is or is thought to be constructed base of a triangle
7 : the main substance in a mixture
8 : a number with reference to which a system of numbers is constructed
9 : a chemical substance (as lime or ammonia) that reacts with an acid to form a salt and turns red litmus paper blue


based; basing

Kids Definition of base (Entry 2 of 3)

: to use as a main place of operation or action The company is based in Ohio.
base on or base upon
: to make or form from a starting point It's based on a true story.


baser; basest

Kids Definition of base (Entry 3 of 3)

1 : of low value and not very good in some ways base metals
2 : not honorable “I'll appeal to his baser instincts, of which he has plenty.”— E. B. White, Charlotte's Web


\ ˈbās How to pronounce base (audio) \
plural bases\ ˈbā-​səz How to pronounce bases (audio) \

Medical Definition of base

1 : that portion of a bodily organ or part by which it is attached to another more central structure of the organism the base of the thumb
2a : the usually inactive ingredient of a preparation serving as the vehicle for the active medicinal preparation the fatty base of an ointment
b : the chief active ingredient of a preparation

called also basis

3a : any of various typically water-soluble and bitter tasting compounds that in solution have a pH greater than 7, are capable of reacting with an acid to form a salt, and are molecules or ions able to take up a proton from an acid or are substances able to give up an unshared pair of electrons to an acid — compare alkali
b : any of the five purine or pyrimidine bases of DNA and RNA that include cytosine, guanine, adenine, thymine, and uracil
4 : freebase

Other Words from base

based \ ˈbāst How to pronounce based (audio) \ adjective

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More from Merriam-Webster on base

Rhyming Dictionary: Words that rhyme with base

Thesaurus: All synonyms and antonyms for base

Spanish Central: Translation of base

Nglish: Translation of base for Spanish Speakers

Britannica English: Translation of base for Arabic Speakers Encyclopedia article about base

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authorized for issue (as a bond)

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