Webster’s Revised Unabridged Dictionary · 1913
Imaginary
Im·ag′i·na·ry, a. [L. imaginarius: cf. F. imaginaire.] Existing only in imagination or fancy; not real; fancied; visionary; ideal.
Wilt thou add to all the griefs I suffer Imaginary ills and fancied tortures? Addison.
Imaginary calculus See under Calculus. — Imaginary expression or quantity (Alg.), an algebraic expression which involves the impossible operation of taking the square root of a negative quantity; as, √-9, a + b √- 1. — Imaginary points, lines, surfaces, etc. (Geom.), points, lines, surfaces, etc., imagined to exist, although by reason of certain changes of a figure they have in fact ceased to have a real existence.
Syn. — Ideal; fanciful; chimerical; visionary; fancied; unreal; illusive.
Im·ag′i·na·ry, n. (Alg.) An imaginary expression or quantity.