proneness

noun

1. (uncountable, usually)The quality or state of being prone, or of bending downward.

   “The proneness of animals is opposed to the erect posture of human beings.”

2. (uncountable, usually)The state of lying with the face down.
3. (dated, uncountable, usually)Descent; declivity.

   “the proneness of a hill”

4. (uncountable, usually)Inclination of mind, heart, or temper; propension; disposition.

   “proneness to self-gratification”