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.

plural of hole in one

(literally) Being seen or targeted, often through the sights of a weapon. / (figuratively) The target or object of one's efforts or ambitions. / (figuratively) Still achievable.

plural of one and only

simple past tense and past participle of one-up

(slang) obsession with a particular person who is idealized as the only right one to date or to marry, often without any actual relationship developments.

That keeps promises and tells the truth.

plural of one-two

(idiomatic, derogatory) Subject to one's demands because of bribery.

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