linoleic acid

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

• noun An unsaturated fatty acid, C₁₈H₃₂O₂, considered essential to the human diet, that is an important component of drying oils, such as linseed oil.

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

• noun an polyunsaturated fatty acid, having 18 carbon atoms and two double bonds, essential for human nutrition; it is found in linseed, sunflower and other vegetable oils

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

• noun a liquid polyunsaturated fatty acid abundant in plant fats and oils; a fatty acid essential for nutrition; used to make soap