(collectible card games) A card included in a deck only once.

present participle of one

(formal) simultaneously, at the same time, all together / (chiefly UK, formal) in agreement

(UK, dated, informal) To be amusing in a slightly challenging way.

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

Initialism of Office for National Statistics.

simple past tense and past participle of on

present participle of on

simple past tense of be a one

Third-person singular simple present indicative form of be a one