car·box·y·he·mo·glo·bin 
(kär-bŏk′sē-hēmə-glō′bĭn)
(kär-bŏk′sē-hēmə-glō′bĭn)n.
The compound that is formed when inhaled carbon monoxide combines with hemoglobin, binding more tightly than oxygen and rendering the hemoglobin incapable of transporting oxygen.