There are 15 13-letter words that start with 'cu'.
Note: These 15 13-letter words that start with 'cu' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with cur, cul, cut, cus, cup, cum, cub, cun, cud, cui, cuc, cuf, cue, cua, cuv, cuk.
3-letter words start with 'cu' (7)