Definitions of shad:

• noun:   herring-like food fishes that migrate from the sea to freshwater to spawn
• noun:   bony flesh of herring-like fish usually caught during their migration to fresh water for spawning; especially of Atlantic coast
• name:  A male given name (rare: 1 in 25000 males; popularity rank in the U.S.: #1164)
• name:  A surname (very rare: popularity rank in the U.S.: #42126)