- -itis is a suffix that means "inflammation" used in medicine, as in tonsillitis. It's transition to its use as sleepiness is unclear, maybe in reference the stomach swelling after a large meal.
itis (2)
clipping NOUN
Extremely sleepy or drowsy state, usually occurs after a large meal.
Etymology : suffix -ITIS.
Source : "I got the itis, I'm not gonna be able to do any work for a while." - Conversation with friend (2011).
Last modified: 2 December 2011