the word 'tedious' entered english in the early 15th century from the old french 'tedieus', which itself derived from the late latin 'taediosus', meaning 'wearisome, irksome'. this latin adjective stems from 'taedium', meaning 'weariness, disgust', a noun related to the verb 'taedere', 'to weary, disgust'. the ultimate origin is uncertain but may be connected to a proto-indo-european root meaning 'to be foul, rotten'. the semantic journey is from a physical sense of disgust or satiety to the modern, more abstract psychological sense of mental weariness caused by something long and monotonous.

the word 'tedious' is a simplex loanword from latin. it does not contain separable morphemes in its modern english spelling that are productive or meaningful to the learner in isolation.