Three characteristics that are unique to mammals include their  ability to feed their babies with milk made in their mammary  glands. Mammals also have hair on their bodies â¦and they have a  single bone that makes up their lower jaw.
buoyancy. n. 1. the ability to float in a liquid or to rise in a fluid. 2. (General Physics) the property of a fluid to exert an upward force (upthrust) on a body that is wholly or partly submerged in it. 3. the ability to recover quickly after setbacks; resilience.
buoyancy - irrepressible liveliness and good spirit; I admired his buoyancy and persistent good humor irrepressibility sprightliness, liveliness, spirit, life - animation and energy in action or expression; it was a heavy play and the actors tried in vain to give life to it