THESAURUS
harden
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
ROGET THESAURUS
harden
Habit
VB
be wont, fall into a rut, fall into a custom, tread the beaten track, follow the beaten track, tread the beaten path, follow the beaten, stare super antiquas vias, move in a rut, run on in a groove, go round like a horse in a mill, go on in the old jog trot way, habituate, inure,
harden, season, caseharden, accustom, familiarize, naturalize, acclimatize, keep one's hand in, train, get into the way, get into the knack of, learn, cling to, adhere to, repeat, acquire a habit, contract a habit, fall into a habit, acquire a trick, contract a trick, fall into a trick, addict oneself to, take to, get into, be habitual, prevail, come into use, become a habit, take root, gain upon one, grow upon one.
Strength
VB
be strong, be stronger, overmatch, render strong, give strength, strengthen, invigorate, brace, nerve, fortify, sustain,
harden, case
harden, steel, gird, screw up, wind up, set up, gird up one's loins, brace up one's loins, recruit, set on one's legs, vivify, refresh, refect, reinforce, reenforce.
Hardness
VB
render hard,
harden, stiffen, indurate, petrify, temper, ossify, vitrify, accrust.