1. (zoology) used of mollusks having two shells (as clams etc.)
   "Oysters are bivalved mollusks prized for their flavour";
   - bivalve
    
2. (botany) having two valves or parts, as in seed pods
   "The bivalved seed pods split open when ripe"

See also: lamellibranch, pelecypod, pelecypodous