·noun Descent; declivity; as, the proneness of a hill.
II. Proneness ·noun The state of lying with the face down;
— opposed to supineness.
III. Proneness ·noun Inclination of mind, heart, or temper; propension; disposition; as, proneness to self-gratification.
IV. Proneness ·noun The quality or state of being prone, or of bending downward; as, the proneness of beasts is opposed to the erectness of man.