What is the meaning of Portcullis?

A gate in the form of a grating which is lowered into place at the entrance to a castle, fort, etc.

An old English coin from the reign of Elizabeth I, minted for the use of the East India Company, and bearing the picture of a portcullis on the reverse.

To obstruct with, or as with, a portcullis; to shut; to bar.

Source: wiktionary.org