A strong natural tendency toward a particular behavior, especially one that is considered negative or undesirable. It implies an almost irresistible inclination that may be difficult to control or change.
From Latin 'proclivitas' meaning 'a slope, tendency downward', derived from 'proclivis' (sloping forward, prone to). The root combines 'pro-' (forward) and 'clivus' (slope, hill). The metaphor of a downward slope suggests something that naturally tends to go in a particular direction, often with negative connotations since entering English in the 16th century.
Proclivity often carries a hint of moral judgment - we don't usually talk about someone's 'proclivity for kindness' but rather their 'proclivity for gambling' or 'violent tendencies'! The word's etymology suggests a downward slope, reflecting the historical view that strong inclinations often lead us away from virtue or self-control.
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