From Longman Dictionary of Contemporary Englishlumbarlum‧bar /ˈlʌmbə $ -ər/ adjective technical HBHMrelating to the lower part of the back pain in the lumbar region
Examples from the Corpus
lumbar• He was in that terrible state of lumbar pain where mobility involves a slow ambulatory squat.• The seats have built-in lumbar supports.Origin lumbar (1600-1700) Modern Latin lumbaris, from Latin lumbus “lower back” 