leu·ke·mi·a (lo?o-k??m?-?)n. Any of various acute or chronic neoplastic diseases of the bone marrow in which unrestrained proliferation of white blood cells occurs, usually accompanied by anemia, impaired blood clotting, and enlargement of the lymph nodes, liver, and spleen.leu·ke?mic adj. & n.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.leu?ke?mi?a (lu?ki mi ?) n. any of several cancers of the bone marrow characterized by an abnormal increase of white blood cells in the tissues. [earlier leuchaemia