Roget's Thesaurus of English Words and Phrases by Peter Mark Roget

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. V. render hard &c adj.; harden, stiffen, indurate, petrify, temper, ossify, vitrify; accrust†. Adj. 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 &c n.; stiff as buckram, stiff as a poker; stiff as starch, stiff as as board.