non·a·no·ic acid (n?n??-n???k)n. See pelargonic acid.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.nonanoic acid (?n?n??n???k) n (Elements & Compounds) a colourless oily fatty acid with a rancid odour: used in making pharmaceuticals, lacquers, and plastics. Formula: CH3(CH2)7COOH. Also called: pelargonic acid [C19: from nonane a paraffin, ninth in the methane series, from Latin n?nus ninth + -ane]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014