nutrition has 6 distinct synonyms spread across 1 of its 3 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. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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.
(physiology) the organic process of nourishing or being nourished; the processes by which an organism assimilates food and uses it for growth and maintenance
a source of materials to nourish the body
the scientific study of food and drink (especially in humans)
Synonyms, antonyms and the broader and narrower relations for nutrition come from Princeton University’s WordNet. Full sources and licences.