filter in Wingdings is ♐︎♓︎●︎⧫︎♏︎❒︎

Any porous substance, as cloth, paper, sand, or charcoal,through which water or other liquid may passed to cleanse it from thesolid or impure matter held in suspension; a chamber or devicecontaining such substance; a strainer; also, a similar device forpurifying air. Filter bed, a pond, the bottom of which is a filtercomposed of sand gravel.-- Filter gallery, an underground gallery or tunnel, alongside of astream, to collect the water that filters through the interveningsand and gravel; -- called also infiltration gallery.