I·saac (??z?k) In the Bible, the son of Abraham who was offered as a sacrifice to God. The sacrifice was prevented at the last moment by divine intervention.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.Isaac (?a?z?k) n (Bible) an Old Testament patriarch, the son of Abraham and Sarah and father of Jacob and Esau (Genesis 17; 21?27)Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014I?saac (?a? z?k) n. a son of Abraham and Sarah, and father of Jacob. Gen. 21:1?4. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.