the.com/catheter

means A thin flexible tube inserted into the body to drain fluids, most commonly urine, when things can't flow out on their own.

from From Greek 'katheter,' meaning 'something let down into,' built from 'kata-' (down) plus 'hienai' (to send or let go). The Greeks originally used it for any instrument lowered into a cavity — the medical sense of a drainage tube is ancient, traced back to Greek physicians who literally sent the tool 'down into' the body.