Libido
The libido or sex drive ( lih-BEE-doh; from Latin libīdō, "lust, desire") refers to a psychological energy that, in common parlance, encompasses all forms of sexual desire, but is sometimes also regarded as the driving force behind other needs, such as a mother's love for her infant. The term was originally developed by the Austrian neurologist Sigmund Freud, the pioneer of psychoanalysis.