warm has 5 distinct synonyms spread across 5 of its 12 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 cool.
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.
having or producing a comfortable and agreeable degree of heat or imparting or maintaining heat
“a warm body”
psychologically warm; friendly and responsive
“a warm greeting”
inducing the impression of warmth; used especially of reds and oranges and yellows when referring to color
“warm reds and yellows and orange”
3 of the 12 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 warm.
Synonyms, antonyms and the broader and narrower relations for warm come from Princeton University’s WordNet. Full sources and licences.