Synonyms of toughened

2 Syllables
temper, season, brass-bound, brassbound, strengthen, anneal, callous
3 Syllables
hardened, thick-skinned, hard-as-nails, develop, inure, shatterproof, seasoned
4 Syllables
unbreakable, climatize, acclimate, infrangible, nonbreakable, brutalize, case-hardened
5 Syllables
acclimatize, casehardened