Solution

TERRIBLY

2 clues

Awfully

Word class: Adverb
Nature of clue: Synonym
Difficulty: Easy
Sources: Boatload Puzzles

Extremely

Word class: Adverb
Nature of clue: Synonym
Difficulty: Very easy
Sources: Boatload Puzzles

Other solutions to Extremely

Words are categorized by artificial intelligence: there can be mistakes.