| Word | Definitions | Synonyms |
|---|---|---|
| frighteningly | (adverb) in a terrifying manner | Synonyms: scarily |
| frightfully | (adverb) used as intensifiers | Synonyms: awful, awfully, terribly |
| frigidly | (adverb) without warmth or enthusiasm | Synonyms: frostily |
| friskily | (adverb) in a playfully frisky manner | - |
| frivolously | (adverb) in a frivolous manner | - |