Wiktionary
constructible
a. 1 Of a land, suitable for constructing a building. 2 Of a building or other thing, capable of being constructed. 3 allowed to construct. 4 (context of a regular polygon English) That can be constructed in a plane using only a pair of compasses and a straightedge. 5 (context of a complex number English) That the line segment joining it to the origin can be constructed using only a pair of compasses and a straightedge.