The term Celtic Priest can be broken down into two crossword solutions: DRUID (5 letters) and ERSE (4 letters). Druids were members of the priestly class in ancient Celtic cultures, such as the Gauls, Britons, and Irish. They were responsible for religious ceremonies, such as sacrifices and divination, as well as for teaching and preserving knowledge. ERSE is an archaic term for Irish, which is the language of the Celts who lived in Ireland.