hot has 5 distinct synonyms spread across 5 of its 21 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. Its one recorded opposite is cold.
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.
used of physical heat; having a high or higher than desirable temperature or giving off heat or feeling or causing a sensation of heat or burning
“hot stove”
characterized by violent and forceful activity or movement; very intense
“the fighting became hot and heavy”
extended meanings; especially of psychological heat; marked by intensity or vehemence especially of passion or enthusiasm
“a hot temper”
14 of the 21 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 hot.
Synonyms, antonyms and the broader and narrower relations for hot come from Princeton University’s WordNet. Full sources and licences.