adjective: Of a land, suitable or allowable for constructing a building on.
adjective: Of a building or other thing, capable of being constructed.
adjective: (of a regular polygon) That can be constructed in a plane using only a pair of compasses and a straightedge.
adjective: (of a complex number) Such that the line segment joining it to the origin can be constructed using only a pair of compasses and a straightedge.