IPA: //ˈtʌfɪst//
KK: /tʌfɪst/
The most strong or difficult to deal with; able to endure hardship or pain better than others.
She is the toughest competitor in the tournament.
Comparative: tougher
Superlative: toughest
Toughest → It is formed from "tough" (from Old English *tōh*, meaning strong or resilient) and the suffix "-est" (meaning the most). The word "toughest" means the most strong or resilient among others.
Think of 'tough' as being strong or resilient, and remember that 'toughest' means the most strong or resilient.