n. The act of walking or moving slowly, or of falling behind.n. In architecture, the planking, consisting of narrow strips, extending from one rib of the centering of an arch, vault, or tunnel to another, and affording direct support to the voussoirs until the arch or vault is closed in.n. In mining, strips of wood or light timbers laid across the stulls in the drifts to prevent fragments of rock from falling through.n. In machinery, same as deading.n. A covering for the face of a pulley, designed to increase its effective diameter or to augment the adhesion of the belt.n. Same as lag, n., 7.n. Nautical, the part of a barrel-stave beyond the head. Also spelled laggin.