stem has 14 distinct synonyms spread across 6 of its 10 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 slender or elongated structure that supports a plant or fungus or a plant part or plant organ
grow out of, have roots in, originate in
“The increase in the national debt stems from the last war”
cause to point inward
“stem your skis”
stop the flow of a liquid
“staunch the blood flow”
Synonyms, antonyms and the broader and narrower relations for stem come from Princeton University’s WordNet. Full sources and licences.
remove the stem from
“for automatic natural language processing, the words must be stemmed”