appall (third-person singular simple present appalls, present participle appalling, simple past and past participle appalled)
1.to fill or overcome with horror, consternation, or fear; dismay, He was appalled by the damage from the fire. I am appalled at your mistakes.
also appal, early 14c., "to fade;" c.1400, "to grow pale," from Old French apalir "become or make pale," from a- "to" (see ad-) + palir "grow pale," from Latin pallere (see pallor). Meaning "cause dismay or shock," is 1530s. Related, Appalled; appalling.
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