linolenic acid

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

• noun An unsaturated fatty acid, C₁₈H₃₀O₂ considered essential to the human diet, that is an important component of natural drying oils.

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

• noun organic chemistry An polyunsaturated fatty acid, having 18 carbon atoms and three double bonds, essential for human nutrition; it is found in linseed and other vegetable oils

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

• noun a liquid polyunsaturated fatty acid that occurs in some plant oils; an essential fatty acid