The American Heritage® Dictionary of the English Language, 4th Edition
n. Any of a class of organic compounds, such as acetone, having a carbonyl group linked to a carbon atom in each of two hydrocarbon radicals and having the general formula R(CO)Rˌ, where R may be the same as Rˌ.
n. A homologous series of organic molecules whose functional group is an oxygen atom joined to a carbon atom—by a double bond—in a carbon-hydrogen based molecule.
the GNU version of the Collaborative International Dictionary of English
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.
The Century Dictionary and Cyclopedia
n. A compound in which the carbonyl group CO unites two alcohol radicals: as, methyl-ethyl ketone, CH3.CO.C2H5.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. any of a class of organic compounds having a carbonyl group linked to a carbon atom in each of two hydrocarbon radicals
Word Usage
"These reactions are caused by enzymes, air or moulds (so - called ketone rancidity)."