acetoacetic acid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A ketone body, C₄H₆O₃, excreted in the urine in certain diabetic conditions.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun organic chemistry The ketonic carboxylic acid CH3-CO-CH2-COOH, that is present in the urine of people suffering from starvation or some forms of diabetes

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun unstable acid found in abnormal amounts in the blood and urine in some cases of impaired metabolism (as diabetes mellitus or starvation)