Leucocyte :: Leucocyte (n.) A colorless corpuscle, as one of the white blood corpuscles, or those found in lymph, marrow of bone, connective tissue, etc..
Leucocythemia :: Leucocythemia (n.) A disease in which the white corpuscles of the blood are largely increased in number, and there is enlargement of the spleen, or the lymphatic glands; leuchaemia..