·noun Natural tendency; affinity; attraction;
— used of inanimate objects.
II. Appetency ·noun Fixed and strong desire; ·esp. natural desire; a craving; an eager appetite.
III. Appetency ·noun Specifically: An instinctive inclination or propensity in animals to perform certain actions, as in the young to suck, in aquatic fowls to enter into water and to swim; the tendency of an organized body to seek what satisfies the wants of its organism.