Definitions for "Pollutant"
Any material entering the environment that has undesired effects.
Undesirable substance introduced into a solid, liquid or gaseous environmental medium totally or partially by human activities. See also contaminant. (after Duffus, 1993)
A pollutant is any substance that renders the atmosphere or water foul or noxious to health.
National Library of Medicine: Specialized Information Services
Keywords:  something
something that pollutes.
Keywords:  factor, order, place
a factor which is out of place, out of order