limb has 3 distinct synonyms spread across 2 of its 6 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.
Synonyms, antonyms and the broader and narrower relations for limb come from Princeton University’s WordNet. Full sources and licences.
any of the main branches arising from the trunk or a bough of a tree
(astronomy) the circumferential edge of the apparent disc of the sun or the moon or a planet
either of the two halves of a bow from handle to tip
“the upper limb of the bow”
the graduated arc that is attached to an instrument for measuring angles
“the limb of the sextant”
any projection that is thought to resemble a human arm
“the arm of the record player”