'appalment' originates from Middle English, formed from the verb 'appallen', ultimately influenced by Old French 'apalir', where the root 'pal' meant 'pale' (to become pale).

'appalment' changed from Middle English verb forms such as 'appallen' and noun usages in Early Modern English and eventually became the modern English noun 'appalment'. The sense shifted from causing paleness to causing shock or dismay.

Initially, it was associated with causing someone to go pale ('to make pale'), but over time it evolved into its current meaning of causing horror, shock, or deep dismay.