terrifying ter·ri·fying UK/ˈtɛɹɪfaɪ.ɪŋ/ US/ˈtɛrʌˌfaɪɪŋ/ fairly common adjective 1. causing extreme terror “a terrifying wail” Synonymsterrific Similaralarming WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). CMU Pronouncing Dictionary. WordNet 2.1 Copyright Princeton University. All rights reserved.