c. 1200, Spainisc, from Spaine "Spain," from Old French Espaigne (see Spaniard) + -ish. Replaced Old English Speonisc. Altered 16c. by influence of Latin. As a noun, "the Spanish language," from late 15c.
For Spanish Main see main. Spanish moss is attested from 1823. Spanish fly, the fabled aphrodisiac (ground-up cantharis blister-beetles), is attested from c. 1600. Spanish-American War was so called in British press speculations early 1898, even before it began in April. For Spanish Inquisition (by c. 1600), see Inquisition.