At one

What is At one?

At one definition and meaning on Dictionary terms:
being or amounting to a single unit or individual or entire thing, item, or object rather than two or more; a single: one woman; one nation; one piece of cake.
being a person, thing, or individual instance or member of a number, kind, group, or category indicated: one member of the party.

existing, acting, or considered as a single unit, entity, or individual.
of the same or having a single kind, nature, or condition: We belong to one team; We are of one resolve.
noting some indefinite day or time in the future: You will see him one day.
a certain (often used in naming a person otherwise unknown or undescribed): One John Smith was chosen.
being a particular, unique, or only individual, item, or unit: I’m looking for the one adviser I can trust.
noting some indefinite day or time in the past: We all had dinner together one evening last week.
of no consequence as to the character, outcome, etc.; the same: It’s all one to me whether they go or not.

the first and lowest whole number, being a cardinal number; unity.
a symbol of this number, as 1 or I.

a single person or thing: If only problems would come one at a time!
a die face or a domino face having one pip.
a one-dollar bill: to change a five-dollar bill for five ones.
(initial capital letter) Neoplatonism. the ultimate reality, seen as a central source of being by whose emanations all entities, spiritual and corporeal, have their existence, the corporeal ones containing the fewest of the emanations.

a person or thing of a number or kind indicated or understood: one of the Elizabethan poets.
(in certain pronominal combinations) a person unless definitely specified otherwise: every one.

(with a defining clause or other qualifying words) a person or a personified being or agency: the evil one; the one I love.
any person indefinitely; anyone: as good as one would desire.
Chiefly British. (used as a substitute for the pronoun I): Mother had been ailing for many months, and one should have realized it.
a person of the speaker’s kind; such as the speaker himself or herself: to press one’s own claims.
something or someone of the kind just mentioned: The portraits are fine ones. Your teachers this semester seem to be good ones.
something available or referred to, especially in the immediate area: Here, take one