Word not found in any official scrabble dictionaries.
"Proal" Definition
Directed or moved forward, as the lower jaw in the act of chewiug: as, the proal mode of mastication, in which the food is acted on as the lower jaw pushes forward: opposed to palinal. See propalinal. E. D. Cope.
Source: Century Dictionary
adjective
Characterized by or involving movement from back to front, especially of the lower jaw in mastication. Contrasted with palinal.
Source: Oxford Dictionary