| filter | |
| 1. n. 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. n. Electronics or software that separates unwanted signals (for example noise) from wanted signals or that attenuates selected frequencies. | |
| 3. n. Any item, mechanism, device or procedure that acts to separate or isolate. | |
| He runs an email filter to catch the junk mail. | |
| 4. n. (figurative) self-restraint in speech. | |
| He's got no filter, and he's always offending people as a result. | |
| 5. n. (mathematics, order theory) A non-empty upper set (of a partially ordered set) which is closed under binary infima (a.k.a. meets). | |
| The collection of cofinite subsets of ℝ is a filter under inclusion: it includes the intersection of every pair of its members, and includes every superset of every cofinite set. | |
| If (1) the universal set (here, the set of natural numbers) were called a "large" set, (2) the superset of any "large" set were also a "large" set, and (3) the intersection of a pair of "large" | |
| 6. v. To sort, sift, or isolate. | |
| 7. v. To diffuse; to cause to be less concentrated or focused. | |
| 8. v. (intransitive) To pass through a filter or to act as though passing through a filter. | |
| 9. v. (intransitive) To move slowly or gradually; to come or go a few at a time. | |
| 10. v. (intransitive) To ride a motorcycle between lanes on a road | |
