The crossword solution for the term 'Buckle, as lumbar' is 'WARP'. This term refers to a type of weaving technique used to create fabric. In this technique, the weft yarn is passed over and under the WARP yarns in an alternating pattern. This creates a strong and durable fabric that is often used in clothing, upholstery, and other items. In the context of lumbar buckles, this weaving technique is used to create a strong and secure fastening system.