toughest
tough-est
adjective
Having the greatest strength or resilience; most difficult to overcome or deal with.
"That was the toughest challenge I've ever faced."
Thesaurus
Synonyms: bad, hard, tough, hooligan, roughneck, yob, yobbo, bully, rowdy, ruffian, yobo, sturdy
Antonyms: tender, untoughened