c. 1300, "to remove from office, especially from royalty," from Old French deposer (12c.), from de- "down" (see de-) + poser "put, place" (see pose (v.1)). Meaning "testify to, attest," especially "give testimony on oath" is from early 15c.; sense of "take testimony from or examine under oath" is from 1560s. Literal sense of "lay down, let fall" (early 15c.) is obsolete. Related: Deposed; deposing.