"flowing profusely" (especially of words), 1660s, with -ive + Latin effus-, stem of effundere "pour forth, spread abroad; to lavish, squander, waste," from assimilated form of ex "out" (see ex-) + fundere "to pour" (from nasalized form of PIE root *gheu- "to pour"). Hence, "with extravagant display of feelings" (1863). Related: Effusively.
