frightful
1 antonym for frightful — opposites grouped by meaning.
Adj — Causing shock, horror, or fear; dreadful.
Antonyms
How to use frightful
The word patterns that sound natural to a native speaker.
The intensifying sense ("a frightful mess") is dated and mostly British; younger speakers rarely use it this way.
Etymology
Built from "fright" plus "-ful" ("full of"), so literally "full of fright" — though today it more often just means "very bad".
Full origin of frightful →