n. A small hole made by the puncture or perforation of a pin; hence, any very small aperture.n. A minute perforation or transparency, as if made with the point of a pin, of which great numbers sometimes appear in the film of a photographic negative from some chemical defect or fault in manipulation.n. In archery, the exact center of the target. Hits in the gold are measured by their distance from the pinhole. Compare pin, n., 2 .