'arrayal' originates from Middle English, ultimately borrowed from Old French 'arer' / 'arayer' (verb) meaning 'to put in order' or 'to array'.

'arrayal' changed from Old French 'arayer' into Middle English forms such as 'arrayen'/'arrayal' and survived into early modern English as the noun 'arrayal' meaning an arrangement or display.

Initially it referred broadly to the action 'to put in order' or 'prepare'; over time it came to be used as a noun for an arrangement or for a person's dress/display, though the word is now rare or archaic.