"spiritual essence, distinct from matter and supposed in the philosophy of Pythagoras and Plato to be diffused throughout the universe, organizing and acting through the whole of it," 1670s, Medieval Latin, literally "soul of the world;" used by Abelard to render Greek psyche tou kosmou. From fem. of Latin animus "the rational soul; life; the mental powers, intelligence" (see animus) + genitive of mundus "universe, world" (see mundane).