small has 12 distinct synonyms spread across 8 of its 13 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 large, big.
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.
relatively moderate, limited, or small
“a small business”
made to seem smaller or less (especially in worth)
“her comments made me feel small”
2 of the 13 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 small.
Synonyms, antonyms and the broader and narrower relations for small come from Princeton University’s WordNet. Full sources and licences.