1. [n]  the syllable naming the seventh (subtonic) note of any musical scale in solmization
2. [n]  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
3. [n]  a light strong gray lustrous corrosion-resistant metallic element used in strong light-weight alloys (as for airplane parts); the main sources are rutile and ilmenite

TI is a 2 letter word that starts with T.