An antipathy is a deep-seated dislike of something or someone. Usually it's a condition that is long-term, innate, and pretty unlikely to change — like your antipathy for the Red Sox.
If you look at the Greek roots of this word — anti- (meaning "against") and pathos (meaning "feeling"), you can see that antipathy is a feeling against someone or something. In general, antipathies are considered feelings that are kept at least somewhat under wraps and are not out on the surface.
