means A sleek marine mammal with flippers that lives in the sea and hauls out on land or ice to rest — or, as a separate word, a device or mark that closes something tightly or proves it authentic.

from Two different words wearing the same coat. The animal comes from Old English 'seolh,' a North Sea creature with cousins across the Germanic languages. The other 'seal' — the wax-stamped, lid-shut kind — sailed in from Old French 'seel,' itself from Latin 'sigillum,' meaning a little figure or mark (a diminutive of 'signum,' a sign). So one seal barks on a rock; the other quietly signs your fate in wax — same spelling, no relation.