A member of the clergy who conducts religious services for an institution, such as a prison or hospital.
A member of the clergy who is connected with a royal court or an aristocratic household.
A member of the clergy attached to a branch of the armed forces.
[Middle English chapelein, from Old French chapelain, from Medieval Latin capellānus, from capella, chapel; see chapel.] chap'lain·cy, chap'lain·ship' n.
1340, from O.Fr. chapelain "clergyman," from M.L. cappellanus "clergyman," orig. "custodian of St. Martin's cloak" (see chapel). Replaced O.E. capellane, from the same M.L. source.