heinous

The story

1. Frankish · derived from*hattjan“to hate”
2. Old French · derived fromhaïr
3. Anglo-Norman · derived fromhainous
4. Middle English · inherited fromheynous
5. English todayheinous

From Middle English heynous, from Anglo-Norman hainous, heinous (compare French haineux) from Old French haïr, hadir (“to hate”) (compare Old French en-hadir (“to become filled with hate”)), from Frankish *hattjan (“to hate”) (compare Middle English hetien). More at hate. The fluctuation between pronunciations with /eɪ/ and /iː/ is old; the former reflects adoption of an unmonophthongised pronunciation of Old French -ai-, while the latter reflects a monophthongised form.