Commonly Used Terms
(Architecturally and otherwise)

WIC - Walk-in closet
Hdr - Header
KS - Knee Space
DW - Dish Washer
Water Closet - an enclosed toilet
CO - Cased opening
Elevation - The exterior side of a house
TJI - Truss, Joist, I-Beam
Truss - Refers to engineered floor system or roof system.Various types (web truss scissor triss,etc.)
T - Treads
R - Riser
Coffered Ceiling - One of a number of recessed, usually square or octagonal panels in a ceiling. Also, can be on the first or second floor. In this case, a short wall would be used to divide or separage.
PT - Pressure treated lumber
SPF - Refers to lumber, Spruce-Pine-Fir