What is "photo-etching"

Photo-etch \Pho`to-etch"\, v. t. [imp. & p. p. Photo-etched; p. pr. & vb. n. Photo-etching.] [Photo- + etch.] To engrave, or make an engraving of, by any photomechanical process involving etching of the plate.

Photo-etching \Pho`to-etch"ing\, n. A photo-engraving produced by any process involving the etching of the plate.