e-book (??bo?ok)n. A book whose contents are in an electronic format.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.e-book n 1. (Computer Science) a book in electronic form 2. (Journalism & Publishing) a book in electronic form vb (Computer Science) (tr) to book (hospital appointments, airline tickets, etc) through the internet [C20: electronic book] ?e-?booking nCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014e-book or eBook or ebook (?i?b?k) , n. 1. a portable electronic device used to download and read books or magazines that are in digital form. 2. a book in digital form. [1980-85]Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.