ti has 5 distinct synonyms spread across 3 of its 3 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 light strong grey lustrous corrosion-resistant metallic element used in strong lightweight alloys (as for airplane parts); the main sources are rutile and ilmenite
shrub with terminal tufts of elongated leaves used locally for thatching and clothing; thick sweet roots are used as food; tropical southeastern Asia, Australia and Hawaii
the syllable naming the seventh (subtonic) note of any musical scale in solmization
Synonyms, antonyms and the broader and narrower relations for ti come from Princeton University’s WordNet. Full sources and licences.