There are 8 13-letter words that start with 'cer'.
| cerebrospinal | ceremonialism | 
| ceremonialist | ceremoniously | 
| certificating | certification | 
| certificatory | ceruloplasmin | 
Note: These 8 13-letter words that start with 'cer' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with cere, cert, cera, cerv, ceru, ceri, cerc, cero, cerm, cern.
4-letter words start with 'cer' (2)