Illusive: Deceptive in appearance, appearing to exist but vanishing as you approach. Hopes, dreams, and goals are most often illusive: "The loss of his driver's license has made Dusty Rhodes' dreams of becoming a stock car racer rather illusive." Illusive goals are not bad if they are not foolish, "Phyllis Limmer devoted most of her later years to the illusive goal of wearing her high school clothes again." Illusion/illusional = given to or characterized by illusions.Illude = to deceive with false hope
Delusive / delusion: refers to having delusions, wholly false beliefs or visions.
Elusive: implies an object that moves away as you approach, escaping capture or confirmation. “Hi, girl, how elusive you have become (como vc anda desaparecida/fugidia) , where have you been these days ?