noun natural tendency; affinity; attraction;
used of inanimate objects.
2. appetency ·noun fixed and strong desire; ·esp. natural desire; a craving; an eager appetite.
3. 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.