Seal

There are three homophones of seal current as nouns, all pronounced IPA: /si:l/. each of which has an associated verb.

• In nature, a seal is a large sea mammal. Seals have flippers and thick fur; they live at sea, but give birth on land. They are usually found in colder waters.
  • The related verb 'to seal' means to hunt seals. This is usually done for their fur.
• In law and formal human communication, a seal is a mark left on, or attached to, a document in place of or additional to a signature. These were commonly made by pressing a ring or a separate object, rather like a medal, into wax. The seal can be the impression ("The letter bears the seal of the Bishop of London") or the object that makes the impression (Victorian gentlemen commonly wore a seal on their watch chains). The Great Seal is the King's seal, which in former times was the supreme stamp of authority.
  • The verb related to this meaning, 'to seal', means 'to fix one's seal to', 'to mark something as one's own possession' or 'to acknowledge authorship of'.
• From this second meaning of seal, and in particular its use to indicate that a door was closed, seal developed its third current meaning: "any means of preventing the passage of gas or liquid into or out of something, esp. at a place where two surfaces meet" (OED).
  • The verb here, often in the form 'to seal off', means 'to close off', 'to prevent any access' [by people, in the case of buildings etc; by liquids, in the case of pipes; or by contaminants in the case of containers, or chemistry laboratories.]