Yes, seal is a Scrabble word!

Verb

1. Make tight; secure against leakage

2. Close with or as if with a seal

3. Decide irrevocably

4. Affix a seal to

5. Cover with varnish

6. Hunt seals

Noun

1. Fastener consisting of a resinous composition that is plastic when warm; used for sealing documents and parcels and letters

2. A device incised to make an impression; used to secure a closing or to authenticate documents

3. The pelt or fur (especially the underfur) of a seal

4. A member of a Naval Special Warfare unit who is trained for unconventional warfare

5. A stamp affixed to a document (as to attest to its authenticity or to seal it)

6. An indication of approved or superior status

7. A finishing coat applied to exclude moisture

8. Fastener that provides a tight and perfect closure

9. Any of numerous marine mammals that come on shore to breed; chiefly of cold regions