1. (v. t.) To make hard or harder; to make firm or compact; to indurate; as, to harden clay or iron.

2. (v. t.) To accustom by labor or suffering to endure with constancy; to strengthen; to stiffen; to inure; also, to confirm in wickedness or shame; to make unimpressionable.

3. (v. i.) To become hard or harder; to acquire solidity, or more compactness; as, mortar hardens by drying.

4. (v. i.) To become confirmed or strengthened, in either a good or a bad sense.

acclimate acclimatize accommodate accustom adapt adjust anneal be tough beef up brace brace up break break in brutalize buttress cake calcify callous case harden caseharden compact concrete condition confirm conform congeal consolidate cornify crystallize densify domesticate domesticize dry endure establish familiarize firm fix fortify fossilize freeze gentle gird habituate hang tough housebreak indurate intensify inure invigorate lapidify lithify naturalize nerve orient orientate ossify petrify prop refresh reinforce reinvigorate restrengthen season set shore up solidify steel stiffen strengthen support sustain tame temper toughen train turn to stone undergird vitrify wont