ENGLISH
REFERENCE

imaginary

adj. · n.
US //ˌɪˈmædʒəˌnɛɹi// UK //ɪmˈædʒɪnəɹi// imag·i·nary
  1. 1 not real (adj.)
    B1 Intermediate

    existing only in your mind or in a story, not in the real world.

    existing only in the imagination; lacking a basis in physical reality.

    Example

    As a child, she had an imaginary friend who went everywhere with her.

    Example

    The novelist created an imaginary kingdom with its own complex history and unique language to serve as the setting for the series.
    Pitfall
    He has an imaginative friend.
    He has an imaginary friend.

    Use 'imaginary' for things that aren't real. Use 'imaginative' to describe a person who has a good imagination.

  2. 2 mathematical numbers (adj.)
    C1 Advanced Technical Math

    used to describe a type of number in math that is a multiple of the square root of minus one.

    relating to the part of a complex number that is a multiple of the imaginary unit (the square root of -1).

    Example

    In this equation, 'i' represents an imaginary number.

    Example

    The student struggled to visualize how imaginary numbers could be plotted on a complex plane alongside real numbers.

    Usage

    Usually placed before the noun 'number' or 'unit'.
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  1. 3 social shared ideas (n.)
    C2 Proficiency Academic

    the collection of ideas, symbols, and stories that a group of people share to understand their society.

    the set of values, symbols, and institutions common to a social group through which they imagine their social whole.

    Example

    The book explores the national imaginary of 19th-century France.

    Example

    Scholars often discuss the 'social imaginary' to explain how modern citizens perceive their connection to millions of strangers within the same state.

    Teacher's tip

    This is a highly specialized term in sociology and philosophy; learners will rarely encounter it in everyday conversation.
Origin

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.

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