n :  a dicarboxylic acid C₁₀H₁₄N₂O₄ that is derived from pyrrole, that is found in the urine in acute porphyria, and that on condensation of four molecules yields uroporphyrin and other porphyrins .
 
 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2004.