hemp has 5 distinct synonyms spread across 2 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.
a plant fiber
any plant of the genus Cannabis; a coarse bushy annual with palmate leaves and clusters of small green flowers; yields tough fibers and narcotic drugs
a rope that is used by a hangman to execute persons who have been condemned to death by hanging
Synonyms, antonyms and the broader and narrower relations for hemp come from Princeton University’s WordNet. Full sources and licences.