Origin of imaginary number
First recorded in 1905–10
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
any complex number of the form i b, where i = √–1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
A type of complex number in which the multiple of i (the square root of -1) is not equal to zero. Examples of imaginary numbers include 4i and 2 - 3i, but not 3 + 0i (which is just 3). See more at complex number.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.