Webster’s Revised Unabridged Dictionary · 1913
Fatuous
Fat′u·ous (făt′ū·ŭs; 135), a. [L. 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.