toughen

1 to increase the ability of (as a muscle) to exert physical force <weight lifting will help toughen those flabby muscles of yours> Synonyms beef (up), fortify, harden, strengthenRelated Words anneal, temper; firm (up), tone (up); energize, invigorate, vitalize; restrengthenNear Antonyms cripple, incapacitate, paralyze; damage, harm, hurt, impair, injure; break down, wear out; sap, undercut, undermineAntonyms debilitate, enervate, enfeeble, weaken

2 to make able to withstand physical hardship, strain, or exposure <hiking every morning through snow and ice toughened him considerably> Synonyms fortify, indurate, inure, season, steel, strengthen, hardenRelated Words acclimate, acclimatize, adapt, adjust; anneal, temper; invigorate, vitalize; immunize; bolster, boost, brace, buttress, enforce, forearm, prop (up), reinforce (also reenforce), support; break in, limber (up), train; accustom, condition, habituate, naturalizeNear Antonyms emasculate, enervate, enfeeble, exhaust, sap, weaken; cripple, debilitate, hamstring, incapacitate; sensitizeAntonyms soften

3 to make more harsh, uncompromising, or severe <attempts to toughen conditions under which waivers from military service would be permitted> Synonyms harden, stiffen, strengthen, harshenNear Antonyms lessen, moderate, softenAntonyms ameliorate, ease