n. [ 1913 Webster ]

1. The quality or state of being prone, or of bending downward; as, the proneness of beasts is opposed to the erectness of man. [ 1913 Webster ]

2. The state of lying with the face down; -- opposed to supineness. [ 1913 Webster ]

3. Descent; declivity; as, the proneness of a hill. [ 1913 Webster ]

4. Inclination of mind, heart, or temper; propension; disposition; as, proneness to self-gratification. [ 1913 Webster ]