(a system for) draining or being drained

seepage

waste liquid matter, sewage etc coming from a factory, town etc

efflux

(a result of) the sending or pouring out (of liquid, e.g. blood)

outpouring

vapour in the atmosphere at or near the earth's surface, thicker than mist and difficult to see through

heavy mist that reduces visibility

any substance like air (used chiefly of those that are not liquid or solid at ordinary temperatures)

something not liquid or solid

a strong-smelling substance produced in glands by male deer, used in the manufacture of perfumes

scent

(US = odor) a pleasant or unpleasant smell

scent

a strong, bad smell; to smell unpleasantly of something

strong odor

the wet, gassy form of water or other liquids

fumes, mist

vapour

fumes, mist