big has 35 distinct synonyms spread across 11 of its 17 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 2 recorded opposites are little, small.
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.
exhibiting self-importance
“big talk”
generous and understanding and tolerant
“a heart big enough to hold no grudges”
given or giving freely
“was a big tipper”
5 of the 17 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 big.
Synonyms, antonyms and the broader and narrower relations for big come from Princeton University’s WordNet. Full sources and licences.