There are 22 8-letter words that start with 'ext'.
| extended | extender | extensor | exterior | 
| external | externes | extincts | extolled | 
| extoller | extorted | extorter | extracts | 
| extrados | extranet | extremer | extremes | 
| extremum | extrorse | extruded | extruder | 
| extrudes | extubate | ||
Note: These 22 8-letter words that start with 'ext' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with extr, exte, exto, exti, extu, exta.
5-letter words start with 'ext' (2)