(intransitive but with prepositional object, literally) To enter by running. / (intransitive but with prepositional object) To collide with.

(transitive, informal, chiefly passive) To arrest; (especially) to track down and arrest. / (transitive, Britain) To use new machinery at less than full speed, preventing damage.

Alternative spelling of run-in (omitting the hyphens from nouns of this type is nonstandard in formal publications but widely seen in unedited writing)

(participial adjective; editing, typography) (not comparable) Having been run in before or behind previous text.

(informal) Consecutively; in a row.

Moving or advancing at a run. / Of a horse, having a running gait; not a trotter or pacer. / Present, current. / Flowing; easy; cursive. / Continuous; ongoing; keeping along step by step.

(colloquial) Approaching; about; roughly.

The action of the verb to run. / The activity of running as a form of exercise, as a sport, or for any other reason.

Present participle of run.

(idiomatic) Of a candidate: potential or likely; worthy of consideration. / (idiomatic) Of a competitor or contestant: still eligible and able to win.