IPA: /ˈtʌfən/
KK: /tʌfən/
To make something stronger or more resilient, often by increasing its toughness or durability.
The coach decided to toughen the training regimen to prepare the team for the championship.
Past: toughened
Past Participle: toughened
Toughen → It is formed from "tough" (of uncertain origin, possibly from Old English *tōh*, meaning strong or resilient) and "-en" (a suffix used to form verbs indicating to make or become). The word "toughen" means to make something stronger or more resilient.
Think of making something strong or resilient — that's what toughen means, as it combines the idea of being strong with the action of making.