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.

plural of number one

simple past tense and past participle of one-up

Used other than figuratively or idiomatically: see on, one, knee. / (idiomatic) At the mercy of someone.

The number 1,000,000.

(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.

plural of ones' complement

(slang, intransitive) To break wind.

(Ulster) An unpredictable person.