What is a demising wall?

Though you might have some trouble finding this term in a dictionary, it is used to describe a party, or common, wall.

What is CDX plywood?

Everyday plywood is graded from A to D. Grade A plywood is perfect, with no knotholes. D grade has gaping knotholes.
CDX plywood has a C side and a D side. It's ugly, and less expensive than the better-looking plywood. Exterior-grade plywood, designated by the letter X, will not de-laminate when wet.

What is the name for the brick architectural detailing adjacent to windows at GHI brick and block homes?

The draft Greenbelt historic district guidelines refers to this detail as 'horizontal brick coursing'. Builders have called it 'corbelling'

What is the origin of the word gazebo?

/g'zi:beu/ a small building, usually in a garden, with a good view.
Early gazebos were often a tower or lantern on the roof of a house, a projecting balcony, or a structure attached to the top of a wall. Only much later was the word applied to a summerhouse, usually one with open sides. To be strict about it, only those edifices with a good view may be given that name; all others are mere shelters.
For more on the entymology of 'gazebo', see Michael Quinion's World Wide Words

What does AHJ stand for?

Authority Having Jurisdiction is usually the county, city, water/sewage authority, or a combination of any of them.

What is habitable space?

Habitable space definition 
In addition, GHI requires habitable space to be constructed with party walls having one-hour fire resistance (usually 5/8" type-X drywall) on the interior exposure, including the attic [IRC §302.1 ]. 3-season sunrooms may not be considered habitable space because their construction does not include a fire-resistant  party wall.

What is the depth of the frost line in Prince George's County?

PG County local amendment §4-247
Footings; Section R-403.1.4, Minimum Depth.
Section R-403.1.4 is amended to read as follows: "Minimum Depth." All exterior footings and foundation systems shall extend below the frost line. All exterior footings shall be placed at Thirty (30) inches below the undisturbed ground.

Exception: Frost-protected footings constructed in accordance with Section R-403.3 and footings and foundations erected on solid rock shall not be required to extend below the frost line. In Seismic Design Categories D1 and D2, interior footings supporting bearing or bracing walls and cast monolithically with a slab on grade shall extend to a depth of not less than Eighteen (18) inches below the top of the slab.

Satellite DISH is an acronyn; what does DISH stand for?

Digital Information Sky Highway