D

Default

Failure to meet an obligation when due or to perform any provision of a lease, mortgage or other agreement.

Demarcation point

The location where a telecommunications provider's network ends and a private network begins

Demised premises

Premises, or parts of real estate, in which an interest or estate has been transferred temporarily, such as an interest in real property conveyed in a lease.

Demolition clause

A clause within a lease denoting the fact that if or when the ground lease has expired, the building will be demolished per such clause. The lessor must notify the tenants within an established time of such condition.

Diffuser

a device for reducing the velocity of air flow from a mechanical duct system supplying air. Its shape is usually circular or square and it is set in the ceiling at predetermined locations to diffuse air within that space.

Duct

A pipe, tube, channel or any other unit necessary for conveying gases, liquids or solid units from one point to another. The term is mostly identified with air-conditioning systems where the transfer of air is necessary. This is accomplished through sheet-metal ducts. The term is also applicable to under-floor duct systems for conveyance of telephone lines and other electrical conductors.