Refers specifically to the wall-mounted urinal fixture in men's restrooms. For 'toilet' (as a fixture) use 马桶 (mǎtǒng); for 'restroom' (as a place) use 厕所 (cèsuǒ) or 卫生间 (wèishēngjiān).
memory
便 ('convenience' — euphemism for bodily waste, as in 大便 'feces' / 小便 'urine') + 池 ('pool / basin') = 'waste pool' / urinal.
