late 14c., "connection, correspondence;" also "act of telling," from Anglo-French relacioun, Old French relacion "report, connection" (14c.), from Latin relationem (nominative relatio) "a bringing back, restoring; a report, proposition," from relatus (see relate). Meaning "person related by blood or marriage" first attested c.1500. Stand-alone phrase no relation "not in the same family" is attested by 1930.
relation re·la·tion (rĭ-lā'shən)
A logical or natural association between two or more things; relevance of one to another; connection.
The connection of people by blood or marriage; kinship.
A person connected to another by blood or marriage; a relative.
The positional relationship of the teeth or other structures in the mouth.