Adjective
nonorientable (not comparable)
(topology) Not able to be oriented.
The Möbius strip is a nonorientable surface.
Through every point of a nonorientable surface there passes a Möbius-like nonorientable strip (with an odd number of half-twists) which is part of that surface.
Any connected sum involving a real projective plane is nonorientable. Source: Internet
The surfaces in the third family are nonorientable. Source: Internet