(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

(idiomatic) To misspeak, to say something embarrassing or wrong, or to make a mistake in public, or a social blunder, that is embarrassing or offensive.

The state of having invested heavily in just one area. / The state of having devoted all of one’s resources to one thing.

(idiomatic) To remain calm, composed, focused, or aware.