a duplicator (trade mark Xerox) that copies graphic matter by the action of light on an electrically charged photoconductive insulating surface in which the latent image is developed with a resinous powder
protective covering consisting, for example, of a layer of boards applied to the studs and joists of a building to strengthen it and serve as a foundation for a weatherproof exterior
an obstruction that stands in the way (and must be removed or surmounted or circumvented)
something immaterial that stands in the way and must be circumvented or surmounted; "lack of imagination is an obstacle to one's advancement"; "the poverty of a district is an obstacle to good education"; "the filibuster was a major obstruction to the success of their plan"