: an abnormal increase in the number of cells (as lymphocytes) in the cerebrospinal fluid

Browse Nearby Words

Cite this Entry

“Pleocytosis.” Merriam-Webster.com Medical Dictionary, Merriam-Webster, https://www.merriam-webster.com/medical/pleocytosis. Accessed 8 Jul. 2026.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!