A kalimavkion (Greek: καλυμμαύχιον), kalymmavchi (καλυμμαύχι), or, by metathesis of the word's internal syllables, kamilavka (Russian: Камила́вка, romanized: Kamilávka), is a clerical headdress worn by Orthodox Christian and Eastern Catholic monks (in which case it is black) or awarded to clergy (in which case it may be red or purple). An approximate equivalent in the Latin Church is the biretta (Latin: biretum/birretum).
In the Byzantine Empire the term kamelaukion (καμηλ(λ)αύκιον or καμιλαύκιον) was a more general one for formal headgear, including items worn by the imperial family.