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.
n Electronics or software that separates unwanted signals (for example noise) from wanted signals or that attenuates selected frequencies.
n Any item, mechanism, device or procedure that acts to separate or isolate.
n (figurative) self-restraint in speech.
n (mathematics, order theory) A non-empty upper set (of a partially ordered set) which is closed under binary infima (a.k.a. meets).
n (photography) A translucent object placed in the light path of a camera to remove certain wavelengths (colors), or a computer program that simulates such an effect.
n A surname from German.