1. extremely; very much
Usage: informal; intensifier
2. in a way that causes dread or fear; frighteningly

Examples

• I’m dreadfully sorry for being late.
• The weather has been dreadfully hot this week.
• She performed dreadfully on the exam.
• The old house creaked dreadfully in the wind.
• He was dreadfully worried about his mother’s health.
• The movie was dreadfully boring.
• The ghost appeared dreadfully before the frightened children.