Matching each member of one set with exactly one member of another set. / (chiefly UK) Involving direct communication between two people.

A personal relationship between two people.

(chiefly Canada, US) Involving direct communication or competition between two people. / (sports) Involving one attacker and one defender. / (mathematics) bijective or injective

A contest involving only one player on each side, especially of an activity often involving teams.

Alternative form of one-on-one

plural of no one's fool

Synonym of nobody's fool

In a single attempt. / (theater) Performed downstage between the frontmost pieces of scenery.

simple past tense and past participle of on

present participle of on