propensity propensity /prəˈpɛnsɪti/

noun

1. A disposition to behave in a certain way  ( aptness , propensity )
   a disposition to behave in a certain way
    The aptness of iron to rust
   the aptness of iron to rust
    The propensity of disease to spread
   the propensity of disease to spread
   
2. A natural inclination  ( leaning , proclivity , propensity )
   a natural inclination
    He has a proclivity for exaggeration
   he has a proclivity for exaggeration
   
3. An inclination to do something  ( leaning , propensity , tendency )
   an inclination to do something
    He felt leanings toward frivolity
   he felt leanings toward frivolity