animus (n.) Look up animus at Dictionary.com
1820, "temper" (usually in a hostile sense), from Latin animus "rational soul, mind, life, mental powers, consciousness, sensibility; courage, desire," related to anima "living being, soul, mind, disposition, passion, courage, anger, spirit, feeling," from PIE root *ane- "to breathe" (source also of Greek anemos "wind," Sanskrit aniti "breathes," Old Irish anal, Welsh anadl "breath," Old Irish animm "soul," Gothic uzanan "to exhale," Old Norse anda "to breathe," Old English eðian "to breathe," Old Church Slavonic vonja "smell, breath," Armenian anjn "soul").

It has no plural. As a term in Jungian psychology for the masculine component of a feminine personality, it dates from 1923. For sense development in Latin, compare Old Norse andi "breath, breathing; current of air; aspiration in speech; soul, spirit, spiritual being."