1610s, "relating to the land," from Middle French loy agrarienne "agrarian law," corresponding to Latin Lex agraria, the Roman law for the division of conquered lands, from agrarius "of the land," from ager (genitive agri) "a field," from PIE *agro- (cognates: Greek agros "field," Gothic akrs, Old English æcer "field;" see acre). Meaning "having to do with cultivated land" first recorded 1792.