omega-3 fatty acidn. Any of several polyunsaturated fatty acids that are essential for human metabolism, have anticoagulant properties, and are found in leafy green vegetables, vegetable oils, nuts, and fish such as salmon and mackerel. Increasing dietary intake of omega-3 fatty acids can decrease serum concentrations of triglycerides and LDL cholesterol while increasing HDL cholesterol.[So called because the first double bond in the chain of carbon atoms in such fatty acids is found between the third and fourth atoms when counted from the omega end of the chain.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.omega-3 fatty acid n (Cookery) an unsaturated fatty acid that occurs naturally in fish oil and is valuable in reducing blood-cholesterol levels Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014o?me?ga-3 fat?ty ac?id (o??mi g???ri, o??me?-, o??m?g ?-) n. a fatty acid found esp. in fish oil and valuable in reducing cholesterol levels in the blood. [1980?85] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.