imaginary number


Definition of imaginary number

: a complex number (such as 2 + 3i) in which the coefficient of the imaginary unit is not zero

called also imaginary

— compare pure imaginary

Examples of imaginary number in a Sentence

Recent Examples on the Web

For example, the solutions to x5 = 1 are five points on a circle when plotted onto a graph comprised of real numbers along one axis and imaginary numbers on the other. Davide Castelvecchi, Scientific American, "“Grand Unified Theory of Math” Nets Abel Prize," 20 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'imaginary number.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of imaginary number

1798, in the meaning defined above

Keep scrolling for more

Learn More about imaginary number

Share imaginary number

Statistics for imaginary number

Look-up Popularity

Time Traveler for imaginary number

The first known use of imaginary number was in 1798

See more words from the same year

More from Merriam-Webster on imaginary number Encyclopedia article about imaginary number

Comments on imaginary number

What made you want to look up imaginary number? Please tell us where you read or heard it (including the quote, if possible).


grandiloquent, ostentatious, or bombastic

Get Word of the Day daily email!

Test Your Vocabulary

Original Meanings Quiz

  • rembrandt-painting-a-young-scholar-and-his-tutor
  • Which of the following is the earliest known sense of the word awe?
True or False

Test your knowledge - and maybe learn something along the way.


Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!