appall

The word 'appall' originates from the Old French 'apalir,' which meant to turn pale. This French term was built upon the Latin elements 'ad-' (to) and 'pallere' (to be pale). The core concept is the physical reaction of turning pale from fear, horror, or shock. Over time in English, the meaning shifted from the literal physical effect to directly describing the cause—the act of horrifying or deeply shocking someone, thus capturing the emotional impact that would once have been visibly signaled by pallor.

The word is a simplex form. It entered English from the Old French verb 'apalir' meaning "to grow pale, become pale," which itself derived from the Latin prefix 'ad-' (to, toward) and the Latin root 'pallidus' (pale).