Perhaps from the base of skelos and optanomai; withered at the front, i.e. A point or prickle (figuratively, a bodily annoyance or disability) -- thorn.
KJV: And lest I should be exalted above measure through the abundance of the revelations, there was given to me a thorn in the flesh, the messenger of Satan to buffet me, lest I should be exalted above measure.
NASB: Because of the surpassing greatness of the revelations, for this reason, to keep me from exalting myself, there was given me a thorn in the flesh, a messenger of Satan to torment me-- to keep me from exalting myself!