The number represented by the Arabic numeral 1; the numerical value equal to that cardinal number.

(number theory) The first positive number in the set of natural numbers.

(set theory) The cardinality of the smallest nonempty set.

(mathematics) The ordinality of an element which has no predecessor, usually called first or number one.

Used for emphasis and can refer to a preeminent example or an unknown person with a specified name.

The digit or figure 1.

(by ellipsis) Used to briefly refer to a noun phrase understood by context, can refer to a one-dollar bill, one o'clock, a run scored in cricket, or a joke or amusing anecdote.

(followed by for) A person (having some specified characteristic or attribute).

(colloquial) A particularly special or compatible person or thing.

(mathematics) The identity element with respect to multiplication in a ring.

(Internet slang, leetspeak, sarcastic) Used instead of ! to amplify an exclamation, parodying unskilled typists who forget to press the shift key while typing exclamation points, thus typing "1".

(impersonal pronoun, indefinite) One thing (among a group of others); one member of a group.

(impersonal pronoun, sometimes with "the") The first mentioned of two things or people, as opposed to the other.

(indefinite personal pronoun) Any person (applying to people in general).

(pronoun) Any person, entity or thing.

(relative, rare) Functions as a relative pronoun at the end of a relative clause.

To cause to become one; to gather into a single whole; to unite.

Of a period of time, being particular.

Being a single, unspecified thing; a; any.

Sole, only.

Whole, entire.

In agreement.

The same.

Used at the end of a sentence to highlight the characteristics of someone or something.

Used at the end of a sentence to highlight the originator of something.

A nominalizer; used to form a noun phrase without a head noun.