pilus has 1 distinct synonym spread across 1 of its 2 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.
any of the cylindrical filaments characteristically growing from the epidermis of a mammal
“there is a hair in my soup”
hairlike structure especially on the surface of a cell or microorganism
Synonyms, antonyms and the broader and narrower relations for pilus come from Princeton University’s WordNet. Full sources and licences.