Filters

Part of speech: noun, verb

Definitions

1. Tools or materials that remove unwanted particles or impurities from air, water, or other substances ; standards or conditions applied to choose or limit items or information
2. Objects or substances designed to cleanse or separate impurities from a mixture ; rules or measures that restrict or determine what is included or excluded in a selection
3. Means of removing contaminants or undesired elements from substances ; specific guidelines or policies that narrow down choices or data based on certain characteristics

Etymology: "Filters" is the plural of "filter," which is a noun and a verb. The noun traces back to a Frankish word, "*filtir," that was close kin to the English word "felt." The link makes sense once you picture the material: early filters were pads of pressed wool, and "felt" itself names a fabric made by matting fibres together until they cling. Medieval Latin then took the Frankish term as "filtrum," and it passed into Middle English as "filtre," with the Old French "feutre," meaning both felt and filter, running alongside it. The word's sense has stretched far beyond cloth. A filter began as a physical strainer for separating solids from liquids, and the same idea of letting some things through while holding others back now covers coffee paper, camera lenses, software that sorts email, and rules that decide which applicants or products make the cut. The second meaning in the list above is that abstract extension: a standard or criterion that sieves a set of items.

Synonyms: screens, sifters, strainers, purifiers, selectors

Antonyms: clogs, blocks, obstructs, impedes, prevents