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late 14c., "judge or authority on civil law," from Old French civilien "of the civil law," created from Latin civilis "relating to a citizen, relating to public life, befitting a citizen; popular, affable, courteous" (see civil). Sense of "non-military person" is attested by 1819 (earlier in this sense was civilian, attested from c.1600 as "non-soldier"). The adjective is from 1640s.