A Quick and Simple Dictionary

filter

1. Noun.  A device which separates a suspended, dissolved, or particulate matter from a fluid, solution, or other substance; any device that separates one substance from another.
2. Noun.  Electronics or software that separates unwanted signals (for example noise) from wanted signals or that attenuates selected frequencies.
3. Noun.  Any item, mechanism, device or procedure that acts to separate or isolate.
4. Noun.  (mathematics, order theory) A non-empty upper set (of a partially ordered set) which is closed under binary infima (a.k.a. meets).
5. Verb.  (transitive) To sort, sift, or isolate.
6. Verb.  (transitive) To diffuse; to cause to be less concentrated or focused.
7. Verb.  (intransitive) To pass through a filter or to act as though passing through a filter.
8. Verb.  (intransitive) To move slowly or gradually; to come or go a few at a time.
9. Verb.  (intransitive) To ride a motorcycle between lanes on a road.