ketone

n. organic compound containing a carbonyl group (Chemistry)

A ketone (pronounced as key tone) is either the functional group characterized by a carbonyl group (O=C) linked to two other carbon atoms or a chemical compound that contains this functional group. A ketone can be generally represented by the formula:R1(CO)R2.A carbonyl carbon bonded to two carbon atoms distinguishes ketones from carboxylic acids, aldehydes, esters, amides, and other oxygen-containing compounds. The double-bond of the carbonyl group distinguishes ketones from alcohols and ethers. The simplest ketone is acetone (systematically named 2-propanone).
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n. ketone, organic compound containing a carbonyl group (Chemistry)

(n.)
One of a large class of organic substances resembling the aldehydes, obtained by the distillation of certain salts of organic acids and consisting of carbonyl (CO) united with two hydrocarbon radicals. In general the ketones are colorless volatile liquids having a pungent ethereal odor.
  

a chemical produced when there is a shortage of insulin in the blood and the body breaks down body fat for energy. High levels of ketones can lead to diabetic ketoacidosis and coma. Sometimes referred to as ketone bodies.