There are 21 11-letter words that start with 'geo'.
Note: These 21 11-letter words that start with 'geo' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with geom, geop, geos, geoc, geod, geol, geot, geog, geob, geoh, geor, geoi.
5-letter words start with 'geo' (2)