mef·e·nam·ic acid (m?f??-n?m??k)n. A crystalline compound, C15H15NO2, used as an anti-inflammatory drug and as an analgesic.[(di)me(thyl) + alteration of phen(yl) + am(inobenzo)ic 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.