Abarim Publications' online Biblical Greek Dictionary
The verb πρεπω (prepo) means to be clearly seen (or heard or smelled) or to be conspicuous. It stems from a Proto-Indo-European root "prep-", to appear or be visible (with no descendants in modern languages).
In Greek, this verb assumed the additional meaning of to be conspicuously alike: to obviously resemble (in form or behavior), and from there it came to mean to be conspicuously fitting or suiting, to clearly have propriety, to be obviously proper. It's used 7 times in the New Testament, see full concordance, and from it derive:
- Together with the adjective ιερος (hieros), sacred (thing): the adjective ιεροπρεπης (hieroprepes), meaning befitting a sacred person (Titus 2:3 only).
- Together with the adjective μεγας (megas), great or large: the adjective μεγαλοπρεπης (megaloprepes), meaning very conspicuously fitting (2 Peter 1:17 only).