seadog

noun

1. A sailor accustomed to the sea.

   The old seadog knew the storm was coming long before the rest of the crew were aware of it.

2. A pirate.

3. A seal. (marine mammal)

4. A charge resembling the talbot but with scales, webbed feet and a broad tail.

5. A dogfish.

6. An omen of bad luck.

7. A white-topped wave in an estuary.