There are 16 11-letter words that start with 'coa'.
| coacervates | coadmitting | coagulating | 
| coagulation | coalescence | coanchoring | 
| coappearing | coaptations | coarctation | 
| coassisting | coastguards | coatdresses | 
| coatimundis | coattending | coattesting | 
| coauthoring | ||
Note: These 16 11-letter words that start with 'coa' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with coal, coas, coat, coac, coag, coad, coar, coap, coax, coan, coau, coae, coam.
4-letter words start with 'coa' (3)