(n)a thin quadrilateral muscle at the junction of the thoracic and lumbar regions; acts to counteract the pull of the diaphragm on the ribs to which it is attached
n. [ L. serratura a sawing, fr. serrare to saw. ] 1. A notching, like that between the teeth of a saw, in the edge of anything. Martyn. [ 1913 Webster ]
2. One of the teeth in a serrated edge; a serration. [ 1913 Webster ]