Imaginary, a.
Etymology: [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, sq. root-9, a + b sq. root-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.
1 other Webster entry under this spelling
Imaginary, n. (Alg.)
An imaginary expression or quantity.
Shades of meaning
Fernald lists imaginary only as an antonym, under real.
He lists it without comment; the entries above explain its neighbors.