LINK / CITE ADD TO WORD LIST. adjective. The definition of aghast is someone or something who has been surprised, awed or horrified. An example of someone who might feel aghast is a person who returns home to find his house has burned down. Helga appeared aghast, then torn. 2  And ever, as the white moon shows her affrighted face from the steep gullies in the blackness overhead, aghast Jonah sees the rearing bowsprit pointing high upward, but soon beat downward again towards the tormented deep.