Very hard native crystalline carbon valued as a gem.

synonym: diamond.

Roget 323: hardness etc. adj.; 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.    ... show more

Roget 159: strength; power etc. 157; energy etc. 171; vigor, force; main force, physical force, brute force; spring, elasticity, tone, tension, tonicity.    stoutness etc. adj.; lustihood^†, stamina, nerve, muscle, sinew, thews and sinews, physique; pith, pithiness; virtility, vitality.    athletics, athleticism^†; gymnastics, feats of strength.    adamant, steel, iron, oak, heart of oak; iron grip; grit, bone.    athlete, gymnast, acrobat; superman, Atlas, Hercules, Antaeus^†, Samson, Cyclops, Goliath; tower of strength; giant refreshed.    strengthening etc. v.; invigoration, refreshment, refocillation^†.    [Science of forces] dynamics, statics.    ... show more

Dutch: diamant
Polish: diament

Impervious to pleas, persuasion, requests, reason:
— He is adamant in his refusal to change his mind.

synonyms: adamantine, inexorable, intransigent.

Roget 323: 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 etc. n.; stiff as buckram, stiff as a poker; stiff as starch, stiff as as board.    ... show more