Filter may refer to:


In chemistry, engineering, or household usage, a device to separate mixtures. See:

• Filter (aquarium), critical components of both freshwater and marine aquaria
• Filter (chemistry), a device (usually a membrane or layer) that is designed to physically block certain objects or substances while letting others through
• Filter paper, a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solids from liquids or air
• Air filter, a device composed of fibrous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air
• Oil filter, a filter to remove contaminants from engine oil, transmission oil, lubricating oil, or hydraulic oil
• Pneumatic filter, a device which removes contaminants from a compressed air stream
• Water filter, removes impurities from water by means of a fine physical barrier, a chemical process or a biological process. Filters cleanse water to various extents for irrigation, drinking water, aquariums, and swimming pools

Der (fachsprachlich meist: das) Filter (nach fr. filtrer, it. feltrare, „durchseihen“; urspr. „durch Filz laufen lassen“ zu germanisch *felt „Filz“) kann ein Gerät, Bauteil oder Baugruppe oder eine Methode sein und kommt auch als Eigenname vor.

Un filtre est un système servant à séparer des éléments dans un flux.

Filter är en samlad benämning på processteg som ändrar ett materials eller en signals egenskaper eller innehåll genom att skilja dess komponenter åt.