There are 13 12-letter words that start with 'thi'.
| thievishness | thimbleberry | thimbleweeds |
| thingamabobs | thingamajigs | thingumajigs |
| thinkingness | thiocyanates | thioridazine |
| thiosulfates | thistledowns | thitherwards |
| thixotropies | ||
Note: These 13 12-letter words that start with 'thi' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with thin, thir, thio, thic, thia, thim, thie, thig, this, thit, thix, thil.
4-letter words start with 'thi' (4)