a porous article or mass, e.g. of paper, sand, etc, through which a gas or liquid is passed to separate out matter in suspension

an apparatus containing a filter medium, such as a car's oil filter or the filter tip of a cigarette

Brit a traffic signal at a road junction consisting of a green arrow which, when illuminated, allows traffic to turn left or right when the main signals are red

to subject (a substance) to the action of a filter

(often + out) to remove (particles, etc) by means of a filter

to pass or move through a filter, or as if through a filter

(often + in/out/through) to move gradually

The children filtered out of assembly

(often + in/out/through) said of information: to become known over a period of time

The news soon filtered through to the public

Brit said of traffic: to turn left or right in the direction of the green arrow while the main lights are still red