heel has 7 distinct synonyms spread across 3 of its 11 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the bottom of a shoe or boot; the back part of a shoe or boot that touches the ground and provides elevation
Synonyms, antonyms and the broader and narrower relations for heel come from Princeton University’s WordNet. Full sources and licences.
the back part of the human foot
one of the crusty ends of a loaf of bread
(golf) the part of the clubhead where it joins the shaft