car·di·ac (kär?d?-?k?)adj.1. Of, near, or relating to the heart: cardiac arteries. See Usage Note at coronary.2. Of or relating to the cardia.n. A person with a heart disorder.[Middle English, from Latin cardiacus, from Greek kardiakos, from kardi?, heart; see kerd- in Indo-European roots.]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.cardiac (?k??d??æk) adj1. (Anatomy) of or relating to the heart2. (Anatomy) of or relating to the portion of the stomach connected to the oesophagusn3. (Medicine) a person with a heart disorder4. (Pharmacology) obsolete a drug that stimulates the heart muscle[C17: from Latin cardiacus, from Greek, from kardia heart]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014car?di?ac (?k?r di?æk) adj. 1. of or pertaining to the heart: cardiac disease. 2. of or pertaining to the esophageal portion of the stomach. n. 3. a person suffering from heart disease. [1400?50; late Middle English (