imaginary

Definition

Existing only in the imagination.

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.

Example Sentences

• "imaginary friend"
• "Unicorns are imaginary."
• "Wilt thou add to all the griefs I suffer / Imaginary ills and fancied tortures?"