tedious (adj.)

"tediousness," 1660s, from Latin taedium "weariness, irksomeness, disgust" (mostly post-classical), which is related to taedet "it is wearisome, it excites loathing" (in Late Latin "be disgusted with, be weary of") and to taedere "to weary," but the whole group is of uncertain etymology. Possible cognates are Old Church Slavonic težo, Lithuanian tingiu, tingėti "to be dull, be listless."