From thunder + -ous.

• (British) IPA: /ˈθʌn.də.ɹəs/
• (America, Canada) IPA: /ˈθʌn.dɚ.əs/
• (Australia) IPA: /ˈθan.də.ɹəs/

thunderous

1. Very loud; that sounds like thunder; thundersome. Also in metaphorical expressions, signifying fury.
   • 1907 August, Robert W[illiam] Chambers, chapter VIII, in The Younger Set, New York, N.Y.: D. Appleton & Company, →OCLC ↗:

     But when the moon rose and the breeze awakened, and the sedges stirred, and the cat's-paws raced across the moonlit ponds, and the far surf off Wonder Head intoned the hymn of the four winds, the trinity, earth and sky and water, became one thunderous symphony—a harmony of sound and colour silvered to a monochrome by the moon.

   • 1930, Norman Lindsay, Redheap, Sydney, N.S.W.: Ure Smith, published 1965, →OCLC ↗, page 85:

     He inflated his chest, twirled his moustache, and thumped the table with a revulsion to thunderous indignation.

   • 1932, Frank Richards, “The Complete Outsider”, in The Magnet:

     Mr Quelch, with a thunderous brow, marched on.

• French: tonitruant
• German: donnernd
• Italian: tonitruante, tonante
• Russian: громовой
• Spanish: atronador, tonante, tonitronante, tronitoso, estruendoso, tronitonante, tonitruante