organic has 5 distinct synonyms spread across 2 of its 7 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 inorganic, functional.
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.
relating or belonging to the class of chemical compounds having a carbon basis
“hydrocarbons are organic compounds”
being or relating to or derived from or having properties characteristic of living organisms
“organic life”
involving or affecting physiology or bodily organs
“an organic disease”
constitutional in the structure of something (especially your physical makeup)
a fertilizer that is derived from animal or vegetable matter
2 of the 7 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 organic.
Synonyms, antonyms and the broader and narrower relations for organic come from Princeton University’s WordNet. Full sources and licences.