1. Loud enough to shake the very earth 
2. Sufficiently significant to affect the whole world
   "earthshaking proposals"
   - world-shaking, world-shattering, earth-shattering

See also: important, loud, significant

• genus Arnica
• genus Arnoseris
• genus Arrhenatherum
• genus Artamus
• genus Artemia
• genus Artemisia
• genus Arthropteris
• genus Artocarpus
• genus Arum
• genus Arundinaria
• genus Arundo
• genus Arvicola
• genus Asarum
• genus Ascaphus
• genus Ascaridia
• genus Ascaris
• genus Asclepias
• genus Ascophyllum
• genus Asimina
• genus Asio
• genus Aspalathus
• genus Asparagus
• genus Aspergillus
• genus Asperula
• genus Asphodeline