prothrombin: a protein in blood plasma that is the inactive precursor of thrombin
protein: any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes
yellow-bellied sapsucker: eastern North American sapsucker having a pale yellow abdomen