c.1600, from French cathéter, from Late Latin catheter "a catheter," from Greek katheter "surgical catheter," literally "anything let down," from stem of kathienai "to let down, thrust in," from kata "down" (see cata-) + stem of hienai "to send" (see jet, v.). Earlier was cathirum (early 15c.), directly from Medieval Latin. Related: Catheterization; catheterized; catheterizing.