early 15c., from Late Latin pusillanimis "having little courage" (used in Church Latin to translate Greek oligopsychos "small-souled"), from Latin pusillis "very weak, little" (diminutive of pullus "young animal;" see foal (n.)) + animus "spirit, courage" (see animus). Related: Pusillanimously; pusillanimousness.[pusillanimous etymology, pusillanimous origin, 英语词源]