stack has 20 distinct synonyms spread across 5 of its 8 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 list in which the next item to be removed is the item most recently stored (LIFO)
a large tall chimney through which combustion gases and smoke can be evacuated
a storage device that handles data so that the next item to be retrieved is the item most recently stored (LIFO)
Synonyms, antonyms and the broader and narrower relations for stack come from Princeton University’s WordNet. Full sources and licences.