There are 4 15-letter words that start with 'arch'.
| archaebacterium | archaeopteryxes |
| archiepiscopate | architecturally |
Note: These 4 15-letter words that start with 'arch' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with archi, archa, arche, archd, archo, archb, archf, archn, archp, archr, archw, archl.
6-letter words start with 'arch' (6)