(slang, Britain, New Zealand, Australia) A secondary lover, a mistress.

An unintended consequence of any action in addition to the intended consequence of that action.

(cricket) the visiting side on a tour

An amphipod, Hyalella azteca, indigenous to the Everglades.

(baseball) To get the third out of an inning.

Having two sides, bilateral. / Reversible. / (algebra) Whose salient properties apply when (the specified object) appears on either side of a given binary operator.

(music) A record, released as a single, with an album track on each side, rather than having a B-side.

(idiomatic) Fighting for or supporting that which is good, just, or benevolent.

(horsemanship) The left-hand side of a horse.

on the other hand; conversely