Animus

Where anima is life energy in general, an animus is that energy individuated, held within a membrane for the use of one person or group. The membrane makes an animus a distinct unit rather than part of an undifferentiated whole, and Marsh identifies it with what she elsewhere calls the personal membrane or endosocial membrane. She rules out the wrong reading of the word: her animus is individuated life and has no correlation to the sense of animus as hostility, nor to the Jungian sense. An animus can be personal, belonging to one individual, or shared, belonging to a group behind a common membrane, which is what lets the same term describe both a single living being and a collective one.

In ordinary English, animus means hostility or ill will, and in Jungian psychology it names the unconscious masculine aspect of a woman's psyche. Marsh sets both aside explicitly and returns to the Latin root, animus as life or spirit, giving it a technical role as individuated life within a membrane. The care she takes to exclude the hostility and Jungian senses is part of the definition itself.