Chaplain
Middle English: from Old French chapelain, from medieval Latin cappellanus, originally denoting a custodian of the cloak of St Martin, from cappella, originally ‘little cloak’ (see chapel).
wiktionary
From Middle English chapeleyn, from Old French chapelain, from Medieval Latin, Late Latin cappellānus, from cappella. Doublet of capelin.
etymonline
chaplain (n.)
mid-14c., "minister of a chapel," from Old French chapelein "clergyman" (Modern French chapelain), from Medieval Latin cappellanus "clergyman," originally "custodian of St. Martin's cloak" (see chapel).
It replaced late Old English capellane (from the same Medieval Latin source), the sense of which was "clergyman who conducts private religious services," originally in great households; this sense continued in chaplain and later was extended to clergymen in military regiments, prisons, etc.
