"involuntary and painful muscle contraction," late 14c., from Old French crampe (13c.), from a Frankish or other Germanic word (compare Old High German krapmhe "cramp, spasm," related to kramph "bent, crooked"), from Proto-Germanic *kramp-, forming many words for "bent, crooked," including, via French, crampon.
Writer's cramp is first attested 1842 as the name of a physical affliction of the hand, in discussions of translations of German medical papers (Stromeyer); also known as scrivener's palsy.
adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy).