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

See also: loud, thunder, unpropitious

• artful
• artfully
• artfulness
• arthralgia
• arthralgic
• arthritic
• arthritis
• arthro-
• arthrocentesis
• arthrodesis
• arthrogram
• arthrography
• arthromere
• arthromeric
• arthropathy
• arthroplasty
• arthropod
• arthropod family
• arthropod genus
• Arthropoda
• arthropodal
• arthropodan
• arthropodous
• Arthropteris
• arthroscope