An Etymological Dictionary of the German Language/geil

by Friedrich Kluge

geil, adj., ‘rank, wanton, obscene, lewd,’ from MidHG. and OHG. geil, ‘of savage strength, wanton, exuberant, merry, joyous’; for the change of meaning on the transition from MidHG. to ModHG. comp. Schimpf. The primary meaning. ‘unrestrained, joyous,’ follows from Goth. gailjan, ‘to rejoice’; comp. OSax. gêl, Du. geil, AS. gâl. To the Teut. cognates Lith. gailùs, ‘passionate, furious, sharp, painful, sympathetic,’ and gailěti-s, ‘to injure’; OSlov. zělu (from gailo), ‘violent,’ adv. zėlo, ‘very’ In the compound Biebergeil appears the MidHG. noun geil, geile, ‘testicle.’