*kar-

also *ker-, Proto-Indo-European root meaning "hard."

It forms all or part of: -ard; Bernard; cancer; canker; carcinogen; carcinoma; careen; chancre; -cracy; Gerard; hard; hardly; hardy; Leonard; Richard; standard.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit karkatah "crab," karkarah "hard;" Greek kratos "strength," kratys "strong;" "hard;" Old English heard, German hart "solid and firm, not soft."