n. The act of making a thing hollow by removing the interior substance or part; the digging out of material, or its removal by any means, so as to form a cavity or hollow: as, the excavation of land by flowing water.n. A hollow or cavity formed by removing the interior substance: as, many animals burrow in excavations of their own forming.n. In engineering, an open cutting, as in a railway, in distinction from a tunnel.n. In zoology, a deep and somewhat irregular hollow with well-defined edges, as if a piece had been taken out of the surface.