/ Dictionary / Index L leukocytosis: Meaning and Definition of Find definitions for: leu•ko•cy•to•sis Pronunciation: (l"kō-sī-tō'sis), [key] — n. Physiol., Pathol. an increase in the number of white blood cells in the blood. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: leukocytosis (Thesaurus) leukocyte leukoderma 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