Turns the target into an insectoid person for a period of time
Entomorphis is a hex which turns the target into an insectoid person for a short time.
This may have been the spell that Harry Potter contemplating using on Dudley Dursley in 1995 "by striking him dumb, grow feelers, and have him scuttle home" when the latter was mocking Harry's nightmares about Cedric Diggory's death.
Behind the scenes
"Entomorphis" most possibly derives from the Greek word "έντομο" (entomo) which means "insect" and the Greek word "μορφή" (morphi) which means "form".