imaginary number
imaginary number, any product of the form ai, in which a is a real number and i is the imaginary unit defined as Square root ofββ1. See numerals and numeral systems.
This article was most recently revised and updated by William L. Hosch.
Citation Information
Article Title:
imaginary number
Website Name:
Encyclopaedia Britannica
Publisher:
Encyclopaedia Britannica, Inc.
Date Published:
02 September 2026
Access Date:
November 13, 2026