mirage
n.an optical illusion caused by hot air that makes you see things that are not there, like water on a dry road. It can also describe a hope or plan that seems real but is impossible to achieve.
n.an optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky. Often used figuratively to describe an illusory hope or unattainable goal.
“The water on the hot road was just a mirage.”
“Thirsty travelers in the desert are often deceived by a mirage that looks like a distant lake.”
“The promise of quick riches proved to be a financial mirage, vanishing as soon as the market experienced its first significant downturn.”
Often used with the verb 'to see' or 'to chase' in both literal and figurative contexts.
An unadapted borrowing from French mirage c. 1812.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.