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1

one

adjective \ ˈwən \

Definition of one

1 :being a single unit or thing
  • one day at a time
  • She is one year old.
2 a :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.
3 a :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
4 a :some 1
  • will see you again one day
b :being a certain individual specified by name
  • one John Doe made a speech
5 :only 2a
  • the one person she wanted to marry

See one defined for English-language learners

See one defined for kids

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Examples of one in a Sentence

  1. There is one minute left in the game.

  2. I have a few one-dollar bills in my purse.

  3. She is one year old.

Recent Examples of one from the Web

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.

Origin and Etymology of one

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

one Synonyms

Synonyms
alone, lone, only, one-off, singular, sole, solitary, special, sui generis, unique
Related Words
single, solo, unaccompanied, unattended; incomparable, inimitable, matchless, peerless, unequaled (or unequalled), unmatched, unparalleled, unrivaled (or unrivalled), unsurpassable, unsurpassed; distinct, distinctive, individual, separate; nonce
Near Antonyms
divers, manifold, multifarious, myriad; assorted, heterogenous, miscellaneous, mixed, motley, patchwork, promiscuous, varied; popular, prevailing, prevalent, rampant; perennial, recurrent, repeated

Other Number-Related Terms

jubilee, myriad, quarantine, score, twain

2

one

noun

Definition of one

1 :the first whole number above zero — see Table of Numbers
2 :the number denoting unity
3 a :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

See one defined for English-language learners

Examples of one in a Sentence

  1. one, two, three, four, …

  2. I don't have any ones. Can you break a five?

  3. I'll be there at one.

Recent Examples of one from the Web

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.

Origin and Etymology of one

see 1one

one Synonyms

Synonyms
bone [slang], buck, clam, dollar, smacker [slang]
Related Words
greenback; dead presidents [slang]

Other Number-Related Terms

jubilee, myriad, quarantine, score, twain

3

one

pronoun

Definition of one

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

See one defined for English-language learners

Using one as a 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

  1. “I'll have an iced tea, please.” “I'll have one, too.”

  2. Their dog died, but they plan to get another one.

  3. “You should wear the blue one.” “The one with the stripes?” “No, the other one.”

  4. I'd like to see the ring next to that one.

  5. Which one did you like better?

  6. He is the one who called the police.

  7. That's one possible answer—but not the only one.

  8. I would like to read more, but one doesn't have the time.

Origin and Etymology of one

see 1one

-one

noun suffix

Definition of -one

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

Origin and Etymology of -one

International Scientific Vocabulary, alteration of -ene

ONE Defined for English Language Learners

one

adjective

Definition of one for English Language Learners

  • : 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

Definition of one for English Language Learners

  • : the number 1

  • : a one-dollar bill

  • : one o'clock

one

pronoun

Definition of one for English Language Learners

  • : that person or thing

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

  • : people in general : any person

ONE Defined for Kids

1

one

adjective \ ˈwən \

Definition of one for Students

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.
2

one

noun

Definition of one for Students

1 :the number denoting a single unit :1
2 :the first in a set or series
3 :a single person or thing
3

one

pronoun

Definition of one for Students

1 :a single member or individual
  • I met one of your friends.
2 :any person One never knows what will happen.

Learn More about one

  1. See words that rhyme with one Thesaurus: All synonyms and antonyms for one Spanish Central: Translation of one Nglish: Translation of one for Spanish speakers Britannica English: Translation of one for Arabic speakers

Seen and Heard

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Usage guide: Using one as a Pronoun
Examples: one in a Sentence