(now rare) To be unfavourable to; to work against.

(idiomatic) To be disadvantageous to someone.

(figuratively) To discover or find something by accident. / (figuratively) To meet somebody by chance.

To think less of (someone) for (something they have done).

Unequivocally and intransigently opposed to.

To stop liking or supporting someone; to become unfriendly towards.

Used other than figuratively or idiomatically: see against, the, law. / (law) Illegal; forbidden by law.

(idiomatic) In a time-restricted manner, to meet a deadline, hurriedly, timed.

(transitive, idiomatic) To rebel or oppose to something formerly supported. / (transitive, intransitive) To set against or in opposition to something.

(woodworking, of sanding or planing a piece of wood) Preventing a smooth, level surface from being formed by raising the nap of the wood or causing larger splinters to form ahead of the cutting tool below the cutting surface.