Why is the ninth month called September?
late 14c., in logic, "a previous proposition from which another follows," from Old French premisse (14c.), from Medieval Latin premissa (propositio or sententia) "(the proposition) set before," noun use of fem. past participle of Latin praemittere "send forward, put before," from prae "before" (see pre-) + mittere "to send" (see mission). In legal documents it meant "matter previously stated" (early 15c.), which in deeds or wills often was a house or building, hence the extended meaning "house or building, with grounds" (1730).
"to state before something else," mid-15c., from premise (n.). Related: Premised; premising.