pipe has 9 distinct synonyms spread across 5 of its 9 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 tube with a small bowl at one end; used for smoking tobacco
a long tube made of metal or plastic that is used to carry water or oil or gas etc.
a tubular wind instrument
the flues and stops on a pipe organ
transport by pipeline
“pipe oil, water, and gas into the desert”
Synonyms, antonyms and the broader and narrower relations for pipe come from Princeton University’s WordNet. Full sources and licences.