Below are the best articles we could find on Anima/Animus.
Analytical psychologist Carl Jung developed a theory of archetypes that live in the unconscious mind of all humans. Within that framework, the anima is considered the unconscious feminine side of men, and the animus the unconscious masculine side of women. Under his theory, an individual’s expression of these two archetypes can be studied and developed to unlock attributes and potentials that the conscious mind might keep hidden or be unaware of.