1. Shallow cracks at closely spaced but irregular intervals on the surface of mortar or concrete. 2. Small cracks in a film of paint or varnish which do not completely penetrate to the substrate or the previous coat. The cracks are in a pattern roughly similar to a checkerboard. 3. In plastering, in a lime finish coat, fine spider-web cracks or fissures; usually caused by insufficient troweling or undergauging. 4. See check. 5. Very small cracks in a flat glass surface, usually along an edge.