# What is the origin of the "imaginary" in imaginary numbers? [duplicate]

When was the imaginary number, i, introduced? Why was it called imaginary? Isn't it just as imaginary as a negative number? Aren't all numbers imaginary, for that matter?

I am not interested in the notation of the number (i or j). I'm interested in why it is called imaginary.

The two questions of which this is supposed to be a copy don't ask why it is called imaginary.

• Useful books on this topic: An Imaginary Tale: The Story of $\sqrt{-1}$ by Paul J. Nahin and Imagining Numbers by Barry Mazur. Jul 12 '21 at 14:42
• @MarioALLEGRANZA. No. I am not interested in the notation of the number. Im interested in why it is called imaginary. Jul 12 '21 at 14:49
• Some argue that Descartes was first to use the name in his La Geometrie (1637) - see Mathword - I. Others, such as Leo Corry, argue that Descartes used the name false but described them as imaginary in the sense that they can only be imagined.
– nwr
Jul 12 '21 at 15:46