1. Make or render deaf
   "The explosion deafened several workers"
    
2. Be unbearably loud
   "a deafening noise"
    
3. Make soundproof
   "deafen a room"

Derived forms: deafens, deafened, deafening

Type of: break, damp, dampen, desensitise [Brit], desensitize, go, soften, sound, weaken