existing only in the imagination or fancy; not real; fancied

an imaginary illness; the imaginary animals in the stories of Dr. Seuss.

Mathematics . imaginary number.

adjective

existing , factual , genuine , physical , real , substantial , true

adjective

abstract , apocryphal , apparitional , assumed , chimerical , deceptive , delusive , dreamed-up , dreamlike , dreamy , fabulous , fancied , fanciful , fantastic , fictional , figmental , fool’s paradise , hallucinatory , hypothetical , ideal , illusive , illusory , imaginative , imagined , legendary , made-up , mythological , nonexistent , notional , phantasmal , phantasmic , quixotic , shadowy , spectral , supposed , supposititious , theoretical , trumped up * , unreal , unsubstantial , visionary , whimsicalnotes:imaginary means not based on fact while imaginative means marked by independence and creativity in thought or action , chimeric , conceptual , fantastical , fictitious , fictive , idealistic , ideational , imaginational , insubstantial , invented , make-believe , mythical , simulated , unrealistic , utopian , veritable