tube has 12 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.
electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope
an electric railway operating below the surface of the ground (usually in a city)
“in Paris the subway system is called the `metro' and in London it is called the `tube' or the `underground'”
provide with a tube or insert a tube into
convey in a tube
“inside Paris, they used to tube mail”
ride or float on an inflated tube
“We tubed down the river on a hot summer day”
Synonyms, antonyms and the broader and narrower relations for tube come from Princeton University’s WordNet. Full sources and licences.