Webster's Revised Unabridged Dictionary · 1913

Fatuous

Fatuous , adjective

[Latin fatuus.]

1.
Feeble in mind; weak; silly; stupid; foolish; fatuitous. — Glanvill
2.
Without reality; illusory, like the ignis fatuus.
Thence fatuous fires and meteors take their birth. — Danham