\ˈbās \
plural bases\ˈbā-səz \

Definition of base 

(Entry 1 of 4)

1a 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)

b : the bottom of something considered as its support : foundation the base of the mountain the lamp's heavy base

c 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

d 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

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

4 heraldry : the lower part of a heraldic field (see field entry 1 sense 3c)

5a : 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) : the place from which a military force draws supplies

(2) : a place where military operations begin

(3) : a permanent military installation a naval base The troops were ordered back to base.

d 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.

e linguistics : root sense 6 "Leave" is the base of the verb "left."

6a in various games : the starting place or goal

b : any one of the four stations at the corners of a baseball or softball infield allowing the batter to reach base

c : a point to be considered His opening remarks touched every base.

7 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

8 finance : a price level at which a security (see security sense 3) previously declining in price resists further decline

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 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

2 : 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


adjective (1)

Definition of base (Entry 3 of 4)

1 archaic : of little height … the cedar stoops not to the base shrub's foot …— Shakespeare

2 obsolete : low in place or position … fall to the base earth from the firmament!— Shakespeare

3 obsolete : bass

4 archaic : baseborn base in kind and born to be a slave.— William Cowper

5 feudalism

a : resembling a villein : servile a base tenant

b : held by villenage base tenure

6a : 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

7a : 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


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


based \ˈbāst \ adjective
baseless \ˈbā-sləs \ 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

America’s largest overseas military base—is in the final stage of a more than decade-long expansion project. Time, "Inside Camp Humphreys, South Korea: America's Largest Overseas Military Base," 13 July 2018 The immigrants walked single-file into a squat gray building at the country's military base to be processed back into their country, along with dozens of others also deported. Colleen Long, The Christian Science Monitor, "Families reunited, then deported to Guatemala," 12 July 2018 In the 1960s, the few Chaggosians in the archipelago were relocated to make way for an American military base on Diego Garcia, the largest of the atolls. Jason Daley, Smithsonian, "Coral Reefs Need Fewer Rats and More Bird Poo," 12 July 2018 The flood of children overwhelmed the federal shelter system to the point that a tent city was hurriedly erected in Tornillo, outside El Paso, and preparations were made to house thousands of additional immigrants at military bases in Texas. Elaine Ayala, San Antonio Express-News, "Unmarked vans, security fences: family reunification proceeds behind curtain of secrecy," 12 July 2018 That's one possible explanation for why Morrison would have tried taking an extra base against Royals left fielder Alex Gordon during Tuesday night's game. Pete Grathoff, kansascity, "Alex Gordon blowing a bubble on the run was almost as impressive as the ensuing throw," 11 July 2018 Number of runners left on base by the Marlins in the last three games, including seven on Tuesday night. Matthew Defranks,, "A Closer Look: Milwaukee Brewers 8, Miami Marlins 4," 11 July 2018 The two companies are now seeking regulatory approval to merge into a wireless giant with a subscriber base comparable to behemoths Verizon Communications Inc. Sarah Krouse, WSJ, "Cellphone Bills Go Up for First Time in Nearly Two Years," 13 July 2018 There was a taste of that here in Russia, with Moscow serving as a main base for tens of thousands of supporters, who traveled at great cost to other cities from there. Martin Rogers, USA TODAY, "Qatar is the World Cup every fan should attend," 13 July 2018

Recent Examples on the Web: Verb

The field is seeded 1-8 based upon their regular-season home run total. USA TODAY, "Home Run Derby field: Bryce Harper headlines slugging showcase," 11 July 2018 One of the other items in my closet that is very London-based is my satchel bag. Jamie Lisanti,, "Fashionable 50," 10 July 2018 Would producers opt for doppelgängers based on look or shoot more for a matching personality? Taylor Mead, House Beautiful, "Who Should Play Your Favorite HGTV Stars In A Movie?," 10 July 2018 On a table, a series of small cardboard stand-up cutouts of characters Kole has created based upon strains of marijuana. Marco Santana,, "Marijuana advocates promote education amidst growing legalization push," 14 July 2018 Nature Tots First Tuesday: Nature theme based learning and play through storytelling, art and crafts, and active play on the playground and splash pad. Mary Lou Cruz,, "Davie area events July 18-28," 14 July 2018 Without division of labor and trade based upon that division, the entire world starves. Phillip Molnar,, "Can the U.S. economy withstand a trade war?," 13 July 2018 Where Trump bases his judgments and opinions on instinct, Johnson is a notorious strategist who has long plotted how to inveigle his way into the United Kingdom’s top job. Dan Stewart, Time, "The 3 Big Takeaways from Donald Trump's Controversial Interview with The Sun," 13 July 2018 The series, set to begin shooting this autumn in New Zealand, will be produced by London based FilmWave for the streaming giant. Scott Roxborough, The Hollywood Reporter, "Netflix to Adapt Dutch Kids Book 'The Letter for the King' as Original Series," 12 July 2018

Recent Examples on the Web: Adjective

Under the new plan, the base monthly rent for tenants eligible for reduced rates will be $130 for an efficiency and $150 for a one-bedroom unit. Bill Leukhardt, Courant Community, "Waiting List Open For Southington Housing Authority Apartments," 13 July 2018 For its new Ginger Zest, Belvedere separately distills fresh ginger, pink grapefruit, lemon, and honey vodkas then blends them with more base spirit, much as a blended whiskey would be made. Elva Ramirez, charlotteobserver, "Flavored vodka is moving on from its whipped cream, PB&J past," 6 July 2018 The IdeaPad 330 is the cheapest model, starting at $249.99 for the base 15-inch model. Chaim Gartenberg, The Verge, "Lenovo has some new IdeaPads for every budget," 11 May 2018 For 2018, Suburban prices begin at $50,200 (plus freight) for the base rear-wheel-drive LS model. G. Chambers Williams Iii, Houston Chronicle, "2018 Suburban: SUVs looks great with Z71 Midnight Edition package," 30 Apr. 2018 For 2018, Suburban prices begin at $50,200 (plus freight) for the base rear-wheel-drive LS model. G. Chambers Williams Iii, star-telegram, "Chevrolet’s 2018 Suburban looks great with the Z71 Midnight Edition package | Fort Worth Star-Telegram," 24 Mar. 2018 That -- a bargain for a veteran rotation defensive tackle -- will now be Spence's base salary with the Dolphins. Armando Salguero, miamiherald, "Defensive tackle was Miami Dolphins biggest post-draft need. Not anymore | Miami Herald," 3 May 2018 Moore's base salary for the 2017-18 school year is $218,657. Kaila Contreras, Houston Chronicle, "Crosby ISD releases separation agreement with former superintendent," 16 Mar. 2018 After that, she will be paid 75% of that base salary, or at least $562,500 per year. David Jesse, Detroit Free Press, "Lou Anna Simon's resignation from MSU comes with lifetime of perks," 25 Jan. 2018

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 1a(1)


1587, in the meaning defined at sense 1

Adjective (1)

14th century, in the meaning defined at sense 1

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

10 Oct 2018

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 3)

: 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 3)

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



English Language Learners Definition of base (Entry 3 of 3)

: not honest or good

of a metal : having low quality and value


\ˈbās \

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 \
plural bases\ˈbā-səz \

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 \ adjective

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Comments on base

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to teach someone the beliefs of a group

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