There are 17 15-letter words that start with 'res'.
Note: These 17 15-letter words that start with 'res' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with rest, rese, resp, resi, reso, resu, resh, resc, resa, resy, resm, resk, resl, resw, ress.
4-letter words start with 'res' (2)