There are 4 15-letter words that start with 'arc'.
| archaebacterium | archaeopteryxes |
| archiepiscopate | architecturally |
Note: These 4 15-letter words that start with 'arc' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with arch, arca, arcu, arct, arcs, arcc, arci, arck, arce, arco.
4-letter words start with 'arc' (3)