thin has 16 distinct synonyms spread across 7 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 4 recorded opposites are thick, fat, full, thicken.
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 relatively small extent from one surface to the opposite or in cross section
“thin wire”
relatively thin in consistency or low in density; not viscous
“air is thin at high altitudes”
(of sound) lacking resonance or volume
“a thin feeble cry”
lose thickness; become thin or thinner
1 of the 13 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for thin.
Synonyms, antonyms and the broader and narrower relations for thin come from Princeton University’s WordNet. Full sources and licences.
take off weight