"hardens" in the verb sense
1. harden, indurate
become hard or harder
"The wax hardened"
2. harden, indurate
make hard or harder
"The cold hardened the butter"
3. temper, harden
harden by reheating and cooling in oil
4. season, harden
"This trip will season even the hardiest traveller"
5. inure, harden, indurate
cause to accept or become hardened to habituate
"He was inured to the cold"
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License