acetic acid

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

• noun A clear, colorless organic acid, C₂H₄O₂, with a distinctive pungent odor, used as a solvent and in the manufacture of rubber, plastics, acetate fibers, pharmaceuticals, and photographic chemicals. It is the chief acid of vinegar.

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

• noun organic chemistry A clear colourless organic acid, CH3COOH, formed by the oxidation of ethanol; it is used as a solvent and has very many industrial applications; it is the major acidic component of vinegar.

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

• noun a colorless pungent liquid widely used in manufacturing plastics and pharmaceuticals