imaginary
UK /ɪˈmæd͡ʒɪnəɹi/ · US /ɪˈmæd͡ʒɪˌn(ɛ)ɹi/ adjective, noun
Forms imaginaries
- adjective Existing only in the imagination. “imaginary friend”
- adjective Relating or belonging to the imagination.
- adjective (mathematics, of a number) Having no real part; that part of a complex number which is a multiple of √ (called imaginary unit).
- noun Imagination; fancy.
- noun (mathematics, countable) An imaginary number.
- noun (sociology) The set of values, institutions, laws, and symbols common to a particular social group and the corresponding society through which people imagine their social whole.
Synonyms
all in one's head complex number complex quantity imaginary number fanciful notional
Etymology
From Middle English ymaginarie, ymagynary, from Latin imāginārius (“relating to images, fancied”), from imāgō, equivalent to imagine + -ary.
The mathematical sense derives from René Descartes's use (of the French imaginaire) in 1637, La Geometrie, to ridicule the notion of regarding non-real roots of polynomials as numbers. Although Descartes' usage was derogatory, the designation stuck even after the concept gained acceptance in the 18th century.
Webster’s 1913
- adjective Existing only in imagination or fancy; not real; fancied; visionary; ideal.
- noun An imaginary expression or quantity.
Etymology [L. imaginarius: cf. F. imaginaire.]
Sources: Wiktionary · WordNet 3.0 · Webster’s 1913 — from the Wiktionary entry “imaginary”, CC BY-SA 4.0. Details