(intransitive, idiomatic, (with "for")) To be on the alert, to be watchful.

presiding as a judge in a court / substituted from a sports event, or waiting to be brought on as a substitute

(sometimes attributive) Something which can be appended to something else.

A spectator, onlooker.

(colloquial, idiomatic, dated) To dress up; to make a show of wealth and/or importance; to be pretentious.

(cricket) The leg side.

Alternative form of onside

Running away, usually from the police; on the run.

(idiomatic) Very loudly; as loudly as (vocally) possible.

(cricket) a fielding position on the leg side, about 70° forward of square, designed to prevent runs from drives or to catch lofted drives