Synonyms for soften

verb

1. To become soft

   dissolve, lessen, diminish, disintegrate, become tender, become mellow, thaw, melt, moderate, bend, give, yield, relax, relent.

   Antonyms stiffen*, solidify, freeze.

2. To make soft

   mollify, mellow, assuage, moisten, modify, palliate, appease, temper, tone down, qualify, lower, tenderize, enfeeble, weaken, deliberate, mash, knead; see also decrease 2.

   Antonyms strengthen*, increase, tone up.