Definition of orientable in US English:

orientable

adjective

  • 1Capable of being oriented.

  • 2Mathematics. Of a surface: such that an oriented figure, when moved around any closed path in the surface, returns to its initial position with the same orientation; not non-orientable; (more widely, of a manifold) capable of being assigned a well-defined global coordinate system.

Origin

Early 20th century; earliest use found in The Times. From orient + -able.