propensity in WordNet English dictionary

1. a disposition to behave in a certain way
   "the aptness of iron to rust"; "the propensity of disease to spread"
   aptness  propensity 
   
2. a natural inclination
   "he has a proclivity for exaggeration"
   proclivity  propensity  leaning 
   
3. an inclination to do something
   "he felt leanings toward frivolity"
   leaning  propensity  tendency