A building extension is typically referred to as an "addition" or "annex." It involves expanding the existing structure to increase living or working space.
A building's extension is a wing. As in, "The hospital is adding a wing". Or, "They named it 'The Gonzo Wing' because Gonzo funded it".
Moving the head back is called extension of the head
Check with your local government for building permits...it may differ from place to place.
Skeg
An annex is an extension of or an addition to a building. A small room off of a main room is an annex, and attics are another type of annex.
You need a building permit before building any kind of extension to your house. You also may need foundations for the building, but this may not be a requirement.
Cape
side of a building called
The Disney brand has the brand extension called the Line Extension Strategy.
it will help in building national unity among the people and there will be no kind of prejudice for caste, creed,religion etc
If you mean the type of file it is called the file extension.
extension