v. 25B6; verb
his health deteriorated : WORSEN, decline, degenerate; fail, slump, slip, go downhill, go backwards, wane, ebb; informal go to pot.
these materials deteriorate if stored wrongly : DECAY, degrade, degenerate, break down, decompose, rot, go off, spoil, perish; break up, disintegrate, crumble, fall apart.
improve.