Sep 24, 2025 ghastly ˈgast-lē 2 syllables uncommon ‹ adjective. terrifyingly horrible to the senses: frightening a ghastly crime… such a life seems ghastly in its emptiness and sterility. adjective. intensely unpleasant, disagreeable, or objectionable a ghastly mistake adjective. resembling a ghost › Origin Middle English gastly, from gasten to terrify.