THESAURUS
anneal, backed, brutalize, cake, calcified, calcify, callous, calloused, case harden, case-hardened, concrete, congeal, cornify, crusted, crusty, crystallized, dry, firm, fossilize, fossilized, granulated, harden, hardened, hornified, incrusted, indurated, inure, lapidified, lapidify, lithify, ossified, ossify, petrified, petrify, reinforced, rigidified, sclerotic, set, solidified, solidify, steel, steeled, stiffened, strengthened, temper, toughen, toughened, vitrified, vitrify
ROGET THESAURUS
Hardness
VB
render hard, harden, stiffen,
indurate, petrify, temper, ossify, vitrify, accrust.
N
hardness, rigidity, renitence, renitency, inflexibility, temper, callosity, durity, induration, petrifaction, lapidification, lapidescence, vitrification, ossification, crystallization, stone, pebble, flint, marble, rock, fossil, crag, crystal, quartz, granite, adamant, bone, cartilage, hardware, heart of oak, block, board, deal board, iron, steel, cast iron, decarbonized iron, wrought iron, nail, brick, concrete, cement, hard, rigid, stubborn, stiff, firm, starch, starched, stark, unbending, unlimber, unyielding, inflexible, tense,
indurate, indurated, gritty, proof, adamant, adamantine, adamantean, concrete, stony, granitic, calculous, lithic, vitreous, horny, corneous, bony, osseous, ossific, cartilaginous, hard as a rock, stiff as buckram, stiff as a poker, stiff as starch, stiff as as board.