TRAP n.
, or partitioned chamber, in a drain, soil pipe, sewer, etc., arranged so that the liquid contents form a seal which prevents passage of air or gas, but permits the flow of liquids.
VALVE n.
One or more membranous partitions, flaps, or folds, which permit the passage of the contents of a vessel or cavity in one direction, but stop or retard the flow in the opposite direction; as, the ileocolic, mitral, and semilunar valves.