In casual use, especially when the topic is Halloween or horror movies, ghastly and ghoulish get lumped together, along with other grisly, gory, and gruesome words beginning with the letter “g.” Ghastly and ghoulish have the definitions “like a ghost” and “like a ghoul,” but it’s the extended meanings we’re concerned with here. Ghastly, often used of acts and events, suggests something shockingly frightful, horrible, or repellent, particularly to the eye. You can be sure a ghastly accident or ghastly murder involved a fair amount of blood and gore. Ghoulish is less frequent, as ghouls are less prominent in American culture than ghosts. A ghoul is a demon originating in Muslim lore, said to dig up graves and feed on human corpses, and ghoulish suggests something that demonstrates monstrous cruelty or a fascination with such: the zombies’ ghoulish mission; ghoulish fascination with serial killer movies.