Yours, Etc.: Origins and Uses of 8 Sign-Offs
"pertaining to or situated near the loins," 1650s, from Modern Latin lumbaris, from Latin lumbus "loin" (see lumbago).
lumbar lum·bar (lŭm'bər, -bär')adj. Of, near, or situated in the part of the back and sides between the lowest ribs and the pelvis.