say it: FRAHYT-fuhl
frightful is an adjective meaning "provoking horror". It carries 3 recorded senses.
provoking horror
“an atrocious automobile accident”
“a frightful crime of decapitation”
“an alarming, even horrifying, picture”
“war is beyond all words horrible”
“an ugly wound”
extreme in degree or extent or amount or impact
“in a frightful hurry”
“spent a frightful amount of money”
colloquialism
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for frightful come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.