imaginary number

Meaning

1. (strict-sense) A number of the form bi, where b is any real number and i denotes the imaginary unit.
2. (broadly) A number of the form a + bi, where a and b are real numbers and b is nonzero.

Synonyms

complex number

imaginary

complex quantity

imaginary part

Translations

imaginäre Zahl

nombre imaginaire

imaginair getal

nombre complexe

número puramente imaginário

número imaginário

nombre imaginaire pur

sanal sayı

komplexe Zahl

φανταστικός αριθμός

samengesteld getal

número imaginario

número complexo

Etymology

The adjective imaginary in this context was first used (as French imaginaire) by René Descartes in 1673, La Geometrie, referring to imaginary numbers in the broad sense, as non-real roots of polynomials. Descartes' usage was derogatory, but the concept later gained acceptance through the work of Leonhard Euler and Carl Friedrich Gauss in the 18th century.