The digit or figure 1. / (mathematics) The neutral element with respect to multiplication in a ring. / (US) A one-dollar bill. / One o'clock, either a.m. or p.m.

Used in contrast to anyone, someone or everyone: not one person; nobody.

(chiefly Britain, Commonwealth of Nations except Canada, Ireland) Alternative form of no one

Not any person or thing whatsoever.

(colloquial) A particularly special or compatible person or thing. / (colloquial) A particular person destined to save the universe or world; the chosen one.

The person or thing.

A specified object, thing or person (especially one further away/over there or known or mentioned later).

A specified object, thing or person (especially one nearby or known).

(often with with) In harmony or unity. / (often with with) In agreement, unanimous, of the same opinion. / (archaic) Into a state of harmony, friendship or reconciliation.

As the first in a number of examples or reasons. / As a single given example, often the most obvious or important one and almost certainly enough to sway the argument, of several reasons for something.