nAllantoin(Chem) A crystalline, transparent, colorless substance found in the allantoic liquid of the fetal calf; -- formerly called allantoic acid and amniotic acid.
***
Century Dictionary and Cyclopedia
nallantoinA crystalline substance (C4H6N4O3) found in the allantoic fluid of the cow; the nitrogenous constituent of the allantoic fluid. It is also obtained from other sources.