WordNet records no synonym and no antonym for endotracheal tube. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
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 catheter that is inserted into the trachea through the mouth or nose in order to maintain an open air passage or to deliver oxygen or to permit the suctioning of mucus or to prevent aspiration of the stomach contents
Synonyms, antonyms and the broader and narrower relations for endotracheal tube come from Princeton University’s WordNet. Full sources and licences.