Phrase guide

imaginary unit

noun · 1 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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1

noun

Meaning 1

An imaginary number (in the case of complex numbers, usually denoted i) that is defined as a solution to the equation x2=-1.

Definition source: English Wiktionary via Wiktextract

Qualifier: quaternion theory

Topics: complex-analysis, mathematics, number-theory, sciences

Examples

  • 2014, Dennis G. Zill, Warren S. Wright, Advanced Engineering Mathematics, Ascend Learning (Jones & Bartlett Learning), 5th Edition, page 793, We now simply say that i is the imaginary unit and define it by the property i2=-1. Using the imaginary unit, we build a general complex number out of two real numbers.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

History

Etymology

So named because it takes on the role of unit for the imaginary part of a complex number.

Across languages

Translations

11 source translations are retained for this English entry.

  • Finnish: imaginaariyksikkö — imaginary number
  • French: unité imaginaire — imaginary number
  • German: imaginäre Einheit — imaginary number
  • Hindi: अधिकल्पित एकक (adhikalpit ekak) — imaginary number
  • Italian: unità immaginaria — imaginary number
  • Japanese: 虚数単位 (kyosū tan'i) — imaginary number
  • Korean: 허수단위 (heosudanwi) — imaginary number
  • Latin: unitas imaginaria — imaginary number
  • Polish: jednostka urojona — imaginary number
  • Russian: мни́мая едини́ца (mnímaja jediníca) — imaginary number
  • Thai: หน่วยจินตภาพ (nùai-jin-dtà-pâap) — imaginary number