twill (n.)

"cloth woven in parallel diagonal lines," early 14c., Scottish and northern English variant of Middle English twile, from Old English twili "woven with double thread, twilled," partial loan-translation of Latin bilix "with a double thread" (with Old English twi- substituted for cognate Latin bi-, both from PIE root *dwo- "two"); the second element from Latin licium "thread," a word of unknown etymology.