harden

amalgamate anneal bake brace buttress cake calcify callous cement close clot coagulate compact congeal consolidate contract crystallize curdle dry firm fix fortify fossilize freeze gird indurate jell nerve ossify petrify precipitate press reinforce set settle solidify starch steel stiffen strengthen temper thicken toughen vitrify

densify

continue dilute discourage dishearten disjoin dissolve dissuade divide enlarge flex hurt let go liquefy loosen melt open separate soften thin unfix unsettle upset weaken

be intolerant indulge spoil

acclimate acclimatize adapt adjust blunt brutalize callous callus coarsen conform deaden develop discipline dull embitter habituate indurate inure numb paralyze roughen season steel stiffen strengthen stun stupefy teach train

case-harden climatize make callous render insensitive

disarrange disorder enliven neglect unfit weaken

be intolerant indulge liquefy melt soften spoil