one

adjective
\ˈwən \

Definition of one 

(Entry 1 of 4)

1 : being a single unit or thing one day at a time She is one year old.

2a : being one in particular early one morning The Grand Canyon is one place I'd like to visit.

b : being preeminently what is indicated one fine person She is one tough teacher.

3a : being the same in kind or quality both of one species "Puma" and "cougar" are different names for one animal.

b(1) : constituting a unified entity of two or more components The combined elements form one substance.

(2) : being in agreement or union am one with you on this

4a : some sense 1 will see you again one day

b : being a certain individual specified by name one John Doe made a speech

5 : only sense 2a the one person she wanted to marry

one

noun

Definition of one (Entry 2 of 4)

1 : the first whole number above zero — see Table of Numbers

2 : the number denoting unity

3a : the first in a set or series often used with an attributive noun day one

b : an article of clothing of a size designated one wears a one

4 : a single person or thing has the one but needs the other

5 : a one-dollar bill

at one

: at harmony : in a state of agreement

for one

: as one example I for one disagree

one

pronoun

Definition of one (Entry 3 of 4)

1 : a certain indefinitely indicated person or thing saw one of his friends

2a : an individual of a vaguely indicated group : anyone at all one never knows

b used as a third person substitute for a first person pronoun I'd like to read more but one doesn't have the time.

3 : a single instance of a specified action felt like belting him one— John Casey

Definition of -one (Entry 4 of 4)

: ketone or related or analogous compound or class of compounds lactone quinone

Keep scrolling for more

Synonyms for one

Synonyms: Adjective

alone, lone, only, singular, sole, solitary, special, sui generis, unique

Synonyms: Noun

buck, clam, dollar

Visit the Thesaurus for More 

Using One as a Pronoun: Usage Guide

Pronoun

Sense 2a is usually a sign of a formal style. A formal style excludes the participation of the reader or hearer; thus one is used where a less formal style might address the reader directly. for the consequences of such choices, one has only oneself to thank — Walker Gibson This generic one has never been common in informal use in either British or American English, and people who start sentences with one often shift to another pronoun more natural to casual discourse. when one is learning the river, he is not allowed to do or think about anything else — Mark Twain Use of one to replace a first-person pronoun—sense 2b—has occasionally been criticized. It is more common in British English than in American. I'm watching this pretty carefully and I hope that the issue will come up in the Lords and one may be able to speak about it — Donald Coggan

Examples of one in a Sentence

Adjective

There is one minute left in the game. I have a few one-dollar bills in my purse. She is one year old.

Noun

one, two, three, four, … I don't have any ones. Can you break a five? I'll be there at one.

Pronoun

“I'll have an iced tea, please.” “I'll have one, too.” Their dog died, but they plan to get another one. “You should wear the blue one.” “The one with the stripes?” “No, the other one.” I'd like to see the ring next to that one. Which one did you like better? He is the one who called the police. That's one possible answer—but not the only one. I would like to read more, but one doesn't have the time.
See More

Recent Examples on the Web: Adjective

Decisions made by engineers today, in other words, will determine not how one car drives but how all cars drive. Johannes Himmelreich, BostonGlobe.com, "The everyday moral challenges of self-driving cars," 30 Mar. 2018 Decisions made by engineers today, in other words, will determine not how one car drives but how all cars drive. Johannes Himmelreich, BostonGlobe.com, "The everyday moral challenges of self-driving cars," 30 Mar. 2018 Decisions made by engineers today, in other words, will determine not how one car drives but how all cars drive. Johannes Himmelreich, BostonGlobe.com, "The everyday moral challenges of self-driving cars," 30 Mar. 2018 Decisions made by engineers today, in other words, will determine not how one car drives but how all cars drive. Johannes Himmelreich, BostonGlobe.com, "The everyday moral challenges of self-driving cars," 30 Mar. 2018 Decisions made by engineers today, in other words, will determine not how one car drives but how all cars drive. Johannes Himmelreich, BostonGlobe.com, "The everyday moral challenges of self-driving cars," 30 Mar. 2018 Decisions made by engineers today, in other words, will determine not how one car drives but how all cars drive. Johannes Himmelreich, BostonGlobe.com, "The everyday moral challenges of self-driving cars," 30 Mar. 2018 Decisions made by engineers today, in other words, will determine not how one car drives but how all cars drive. Johannes Himmelreich, BostonGlobe.com, "The everyday moral challenges of self-driving cars," 30 Mar. 2018 Decisions made by engineers today, in other words, will determine not how one car drives but how all cars drive. Johannes Himmelreich, BostonGlobe.com, "The everyday moral challenges of self-driving cars," 30 Mar. 2018

Recent Examples on the Web: Noun

The current culvert was put in about 15 inches higher than the previous one, causing the water issues. Karen Caffarini, Post-Tribune, "About 100 fish found dead in Bon Aire Lake: Merrillville official," 13 July 2018 Your old buddies—the ones with weird hair but brilliant ideas and total loyalty, will have to be hidden in the basement. The Economist, "Life as you know it is IPOver," 12 July 2018 To be sure, there are an increasing number of American Jews, especially young ones, who have chosen their side. Abraham Riesman, Daily Intelligencer, "Can the young activists of IfNotNow change the conversation about Israel and the Palestinians, or will their contradictions hold them back?," 12 July 2018 And so, old seats are being removed this week and new ones, being fabricated by Ducharme Seating in the Montréal borough of Saint-Leonard, will arrive shortly. Peter Dobrin, Philly.com, "Academy of Music is replacing its lumpy old seats - and, no, you're not getting cup holders," 12 July 2018 This one — happening to our neighbors — will be harder to hide. Fabiola Santiago, miamiherald, "Another separation crisis looms – this time for some 273,000 American children," 12 July 2018 Similarly, Netflix has brought back cult classic shows like Arrested Development, pleasing die-hard fans and attracting new ones, too. Hanna Lustig, Teen Vogue, "“The Kissing Booth” Sequel: Everything We Know About the Possible Movie," 12 July 2018 The event — and recently, another one like it in New York — gave Tone It Up’s founders a chance to promote their brand and offer attendees a solid heart-rate-raising time. Tara Paniogue, latimes.com, "Tone It Up brand offers '70s summer vibe and more with new activewear and swimwear collaborations," 11 July 2018 The change is the next one in a wave of conversions of streets from one-way to two ways the city has been going through for several years now. Steve Lord, Aurora Beacon-News, "Aurora set to make Downer Place a two-way street through East Side," 10 July 2018

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

See More

First Known Use of one

Adjective

before the 12th century, in the meaning defined at sense 1

Noun

before the 12th century, in the meaning defined at sense 1

Pronoun

13th century, in the meaning defined at sense 1

History and Etymology for one

Adjective

Middle English on, an, from Old English ān; akin to Old High German ein one, Latin unus (Old Latin oinos), Sanskrit eka

Noun

see one entry 1

Pronoun

see one entry 1

Noun suffix

International Scientific Vocabulary, alteration of -ene

Keep scrolling for more

Learn More about one

Statistics for one

Look-up Popularity

Time Traveler for one

The first known use of one was before the 12th century

See more words from the same century

Keep scrolling for more

More Definitions for one

one

adjective

English Language Learners Definition of one

 (Entry 1 of 3)

: having the value of 1

—used to refer to a single person or thing

—used before a noun to indicate that someone or something is part of a group of similar people or things

one

noun

English Language Learners Definition of one (Entry 2 of 3)

: the number 1

: a one-dollar bill

: one o'clock

one

pronoun

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

: that person or thing

: someone or something that is a part of a particular group

: people in general : any person

one

adjective
\ˈwən \

Kids Definition of one

 (Entry 1 of 3)

1 : being a single unit or thing There's one catch.

2 : being a certain unit or thing He arrived early one morning.

3 : being the same in kind or quality All the members of one class will sit together.

4 : not specified We'll meet again one day.

one

noun

Kids Definition of one (Entry 2 of 3)

1 : the number denoting a single unit : 1

2 : the first in a set or series

3 : a single person or thing

one

pronoun

Kids Definition of one (Entry 3 of 3)

1 : a single member or individual I met one of your friends.

2 : any person One never knows what will happen.

Keep scrolling for more

Comments on one

What made you want to look up one? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

lying above or upon

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Roman Mythology Quiz

  • the-triumph-of-venus-by-alessandro-magnasco
  • Boreal comes from the name of the ancient Greek god of which wind?
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!