equatorial has no recorded synonym. 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. Its one recorded opposite is polar.
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.
of or existing at or near the geographic equator
“equatorial Africa”
a telescope whose mounting has only two axes of motion, one parallel to the Earth's axis and the other one at right angles to it
2 of the 4 recorded senses carry no synonym, antonym or related term, so they are not shown above. Every sense, with its definition and examples, is on the full entry for equatorial.
Synonyms, antonyms and the broader and narrower relations for equatorial come from Princeton University’s WordNet. Full sources and licences.