Desire was an emotion characterized by wishing for something or wanting for something to happen. Sexual desire was a type of desire.
The Talosians of Talos IV were capable of reaching into the minds of their specimens and creating an illusion out of an individual's desires for them to relive. (TOS: "The Cage", "The Menagerie, Part II")
The cilium-like vegetation that inhabited Murder Planet had the ability to fabricate the desires of its intended victims onto its cilium. (PRO: "Dream Catcher")