Synoniemen.net

verharden (ww):
endurecer(en) to become or make less sensitive.
(en) to make hard(er).
(en) to become hard., acostumbrar(en) to cause to become accustomed to something unpleasant by prolonged exposure., avezar(en) to cause to become accustomed to something unpleasant by prolonged exposure., fortalecer(en) to gel or harden., habituar(en) to cause to become accustomed to something unpleasant by prolonged exposure.

Via: Dbnary en WikiWoordenboeken