Of a kite: having more than one flat surface (rare). Of an aircraft or its design: having two or more wings placed one above another.

Designating or relating to a technique in which several images in distinct planes or layers are used to give an enhanced impression of perspective, used especially for animated films.

Generally. Involving or occupying several distinct planes, layers, or levels (not necessarily horizontal).

An aircraft having two or more sets of wings placed one above another (as in a biplane or triplane).