Harden

kovettaa

(to make hard(er))

kovettaa

(to become or make less sensitive)

kovettua

(to become hard)

lujittaa

(to make hard(er))

lujittua

(to become hard)

turruttaa

(to become or make less sensitive)

turtua

(to become or make less sensitive)

vahvistaa

(figurative: to strengthen)

vahvistaa suojausta

(computing: to modify to make resistant to malicious attacks)