Seal

1. Any of numerous marine mammals that come on shore to breed. Harbor seals tend to be quite noisy.
2. A die or signet having a raised or incised emblem used to stamp an impression on a receptive substance such as wax or lead. The King put his seal on the document.
3. A substance, especially an adhesive agent such as wax or putty, used to close or secure something or to prevent seepage of moisture or air. When canning fruit you must seal the jar and use a water bath.
4. To apply a waterproof coating. You should seal your the blacktop driveway.