Illusional and Mirage

Illusional adjective - Marked by or producing illusion.

Mirage and illusional are semantically related. In some cases you can use "Mirage" instead a noun "Illusional".

Mirage noun - An optical illusion in which atmospheric refraction by a layer of hot air distorts or inverts reflections of distant objects.

Illusional and mirage are semantically related. Sometimes you can replace term "Illusional" with "Mirage", this nouns are similar.