TRANSIENT a.
before the sight or perception, or, as it were, moving over or across a space or scene viewed, and then disappearing; hence, of short duration; not permanent; not lasting or durable; not stationary; passing; fleeting; brief; transitory; as, transient pleasure. "Measured this transient world." Milton.…
TRAP n. 2 definitions
A bend, sag, 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.