Imaginary, fanciful, visionary, fantastic, chimerical, quixotic are comparable when they are applied to conceptions or to the persons who form the conceptions and mean unreal or unbelievable and out of keeping with things as they are or conceiving such unreal or unbelievable things.
Something is imaginary which is fictitious and purely the product of an active or an excited imagination.
Something is or, less often, one is fanciful which or who indicates a giving rein to the power of conceiving or producing things that have no real counterpart in nature or in fact.
Something is visionary which, although it seems real and practical to the one who conceives it, is usually the product of a dream or vision or of an unrestrained imagination and is incapable of realization.
One is visionary who is given to such dreams, visions, and fancies and inspired by the hopes they arouse.
Something is fantastic (see also FANTASTIC 2 ) which is or, more often, seems extravagantly fanciful or queer and hence incapable of belief or, sometimes, approval.
Something is chimerical which is wildly or fantastically visionary or unreal.
Something is or one is quixotic which or who is motivated by extravagantly chivalrous devotion to visionary ideals.