: having or showing clear ideas about what should happen or be done in the future. : having or showing a powerful imagination. : of or relating to something that is seen or imagined in a dream or vision (sense 3).ull Definition of VISIONARY. 1. a: of the nature of a vision: illusory c: existing only in imagination: unreal. 2. a: able or likely to see visions b: disposed to reverie or imagining: dreamy. 3. : of, relating to, or characterized by visions or the power of vision.