Early 17th century; earliest use found in Edward Brerewood (c1565–1613), antiquary and mathematician. From post-classical Latin Socinianus from Socinus, Latininized form of the surname of Laelius and Faustus Socinus (Italian Lelio and Fausto Socini, also Soccini, Sozini, Sozzini), two Italian theologians of the 16th cent. + classical Latin -ānus.