Other forms: deafeningly
When a sound is deafening, it's overwhelmingly loud. You may think you're prepared after a flash of lightning, but the deafening sound of thunder can still make you jump!
Deafening noises are so loud that they block out all other sounds. The deafening siren from a passing ambulance easily overwhelms the quiet conversation at your breakfast table, and a deafening roar inside a music venue may make you regret your decision to see your favorite band live. While deafen means "make deaf," deafening generally means something closer to "making you temporarily unable to hear."