to become physically firm or solid <the glue begins to harden as soon as it is exposed to air> Related Words cake
to make able to withstand physical hardship, strain, or exposure <pioneer women who had been hardened by years of living on the plains> Related Words acclimate
; break in
to increase the ability of (as a muscle) to exert physical force <arm muscles that were hardened by all the years of casting and hauling his fishing nets>
to make more harsh, uncompromising, or severe <the government hardened restrictions on travel to and from the war-torn nation>
Seen & Heard
What made you want to look up harden? Please tell us where you read or heard it (including the quote, if possible).