(mathematics, of a function) Having the property that the same argument may yield multiple values, but different arguments never yield the same value.

(mathematics, logic, of a relationship between two sets) having the property that many elements of one set may be assigned by the relationship to one element in the other set, and that a given element in the first set can be assigned by only one member of the second set.

That one has chosen, or wishes to choose.

plural of one-of

Synonym of nobody's fool

(slang) To fart.

Using only one hand.

The quality of having a dominant hand; left-handedness or right-handedness. / Chirality / The possession of only one hand or the ability to use only one hand; the loss of the use of one hand.

(chemistry) Taking place in a single reaction vessel

(idiomatic) Alone; without aid or accompaniment.