In a single session; finishing a task in the same period when one sets out to do so.

One day, some day (especially in warning of a negative consequence).

(informal) In one's opinion. / Used other than figuratively or idiomatically: see in, one's, book.

(idiomatic, colloquial, dated) To drink alcohol excessively, to the point of being drunk

(literally) Onto or into someone's face. / (idiomatic) In front of someone's face; before someone's eyes.

plural of one-nighter

Synonym of one-night stand (single evening's performance) / Synonym of one-night stand (single sexual encounter)

(idiomatic, chiefly Northern England) on one's own, alone

Having only one hand. / Performed using only one hand. / Designed for use with one hand / (specifically, of reading or reading material) Pornographic in nature. / That uses one hand.

Using only one hand; one-handedly. / (figuratively) Very easily, without effort.