An example of someone who might feel aghast is a person who returns home to find his house has burned down.
Origin of aghastMiddle English agast, past participle of agasten, to terrify from a-, intensive + gasten from Old English gaestan, to terrify from gast, ghost
Origin of aghastMiddle English agast past participle of agasten to frighten a- intensive pref. ( from Old English ā- ) gasten to frighten ( from Old English gǣstan ) ( from gāst ghost )
(comparative more aghast, superlative most aghast)
From Middle English agast, agasted, past participle of agasten (“to terrify”), from Old English prefix a- (compare with Gothic - (us-), German er-, originally meaning "out") + gæstan (“to terrify, torment”): compare Gothic (usgaisjan, “to terrify”, literally “to fix, to root to the spot with terror”); akin to Latin haerere (“to stick fast, cling”). See gaze, hesitate.