/ Dictionary / Index L lumbar puncture: Meaning and Definition of Find definitions for: lum'bar punc'ture Pronunciation: [key] puncture into the arachnoid membrane of the spinal cord, in the lumbar region, and withdrawal of spinal fluid, performed for diagnosis of the fluid, injection of dye for imaging, or administration of anesthesia or medication. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. lumbar plexus lumber Related Content Daily Word Quiz: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language