1. noun /ˈfɪltə,ˈfɪltɚ/
a) 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.
The collection of cofinite subsets of ℝ<!should not be italicized is a filter under inclusion: it includes the intersection of every pair of its members, and includes every superset of every cofinite set.
b) Electronics or software that separates unwanted signals (for example noise) from wanted signals or that attenuates selected frequencies.
2. verb /ˈfɪltə,ˈfɪltɚ/
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