—n.
1 a porous device for removing impurities or solid particles from a liquid or gas passed through it.
2 = filter tip.
3 a screen or attachment for absorbing or modifying light, X-rays, etc.
4 a device for suppressing electrical or sound waves of frequencies not required.
5 Brit. a an arrangement for filtering traffic. b a traffic-light signalling this.
—v.intr. & tr.
1 pass or cause to pass through a filter.
2 (foll. by through, into, etc.) make way gradually.
3 (foll. by out) leak or cause to leak.
4 Brit. allow (traffic) or (of traffic) be allowed to pass to the left or right at a junction while traffic going straight ahead is halted (esp. at traffic lights).
Phrases and idioms:
filter-bed a tank or pond containing a layer of sand etc. for filtering large quantities of liquid. filter-paper porous paper for filtering. filter tip
1 a filter attached to a cigarette for removing impurities from the inhaled smoke.
2 a cigarette with this. filter-tipped having a filter tip.
Etymology: F filtre f. med.L filtrum felt used as a filter, f. WG
Useful english dictionary. 2012.