WordNet sense 1 (the pelt or fur (especially the underfur) of a seal):

sealskin

WordNet sense 2 (a member of a Naval Special Warfare unit who is trained for unconventional warfare):

Navy SEAL

WordNet sense 3 (an indication of approved or superior status):

cachet, seal of approval

WordNet sense 4 (fastener consisting of a resinous composition that is plastic when warm; used for sealing documents and parcels and letters):

sealing wax

WordNet sense 5 (a device incised to make an impression; used to secure a closing or to authenticate documents):

stamp

WordNet sense 6 (make tight; secure against leakage):

seal off

WordNet sense 7 (cover with varnish):

varnish