Main entry: propensity, aptness
Definition: a disposition to behave in a certain way
Usage: the aptness of iron to rust; the propensity of disease to spread
Main entry: proclivity, propensity, leaning
Definition: a natural inclination
Usage: he has a proclivity for exaggeration
Main entry: leaning, tendency, propensity
Definition: an inclination to do something
Usage: he felt leanings toward frivolity