1. in psychoanalytic theory, either the psychic energy of the life instinct in general or the energy of the sexual instinct in particular. In his first formulation, Sigmund Freud conceived of this energy as narrowly sexual, but subsequently he broadened the concept to include all expressions of love, pleasure, and self-preservation. See also Eros.

2. in the analytic psychology of Carl Jung, the general life force that provides energy for all types of activities: biological, sexual, social, cultural, and creative.

3. more generally, sexual energy or desire. —libidinal adj. —libidinize vb. —libidinous adj.