1. Loud enough to cause (temporary) hearing loss
   - deafening, earsplitting, thundery 
2. Extremely ominous
   "world events of thunderous import"

See also: loud, thunder, unpropitious

• optical rotation
• Inverness
• inverse
• inverse cosecant
• inverse cosine
• inverse cotangent
• inverse function
• inverse secant
• inverse sine
• inverse tangent
• inversely
• inversion
• invert
• invert soap
• invert sugar
• invertase
• invertebrate
• invertebrate foot
• inverted
• inverted comma
• inverted hang
• inverted pleat
• inverter
• invertible
• invest