The Oxford Thesaurus An A-Z Dictionary of Synonyms - decay v.

1) a decline, wane, ebb, dwindle, diminish, decrease: The magnetic field rapidly decays when the power is removed. b decline, waste away, atrophy, weaken, wither, degenerate, deteriorate, disintegrate; crumble: Her great beauty decayed quickly. 2) rot, decompose, moulder, putrefy, spoil; turn, go bad, go off: The flesh has decayed and only a skeleton remains. --n. 3) decline, weakening, failing, fading, deterioration, decadence, degeneration, wasting, atrophy, dilapidation, disintegration, collapse; downfall: The buildings were in an advanced state of decay. 4) rot, rotting, decomposition, mould, putrefaction, mortification: The decay has weakened the timbers supporting the bridge.