1766, "allege to be of unsound mind" (legal term), from Late Latin stultificare "turn into foolishness," from Latin stultus "foolish" (literally "uneducated, unmovable," from suffixed form of PIE root *stel- "to put, stand, put in order," with derivatives referring to a standing object or place) + combining form of facere "to make, to do" (from PIE root *dhe- "to set, put"). The first element is cognate with Latin stolidus "slow, dull, obtuse" (see stolid). Meaning "cause to appear foolish or absurd" is from 1809. Hence stultiloquy "foolish talk, silly babbling" (1650s). Related: Stultified; stultifying.