mirage

noun
  1. An optical illusion caused by atmospheric conditions, especially the appearance of a sheet of water in a desert or on a hot road, caused by the refraction of light from the sky by heated air. noun
    As they traveled across the desert, they saw what seemed like a lake in the distance, but it was just a mirage.
    The road ahead appeared to be wet, but it was merely a mirage created by the heat.
  2. Something that appears real or possible but is not in fact so; an illusion or unattainable hope. noun
    The promise of quick riches was just a mirage that led many to financial ruin.
    Her dreams of a perfect life were nothing more than a mirage, as reality proved to be much harsher.