1818, "an inner court open to the sky" in Spanish and Spanish-American countries, from Spanish patio probably from Old Provençal patu, pati "untilled land, communal pasture," from Latin pactum "agreement, contract, covenant," noun use of neuter past participle of pacisci "to covenant, to agree, make a treaty," from PIE root *pag- "to fasten." Another theory traces the Spanish word to Latin patere "to lie open." Meaning "paved and enclosed terrace beside a building" is recorded by 1941. Patio furniture is attested from 1924 in California newspaper advertisements; patio door by 1973.