Found 2 items, similar to frightfully.
English → English (WordNet) Definition: frightfully frightfully adv : used as intensifiers; “terribly interesting”; “I'm awful sorry” [syn: terribly, awfully, awful]
English → English (gcide) Definition: Frightfully Frightfully \Fright"ful*ly\, adv. In a frightful manner; to a frightful dagree. [1913 Webster]