filter
UK[ˈfɪltə]US[ˈfɪltər]
n
a device containing paper, sand, chemicals, etc. that a liquid or gas is passed through in order to remove any materials that are not wanted
n
a device that allows only particular types of light or sound to pass through it
v
to pass a liquid, gas, light, or sound through a device in order to remove particular substances contained in it
v
to move gradually in or out of a place or through a group of people
Etymology
The word 'filter' entered English in the late 14th century from Medieval Latin 'filtrum', which meant "felt," a type of porous textile used for straining liquids. This Latin term is believed to be of West Germanic origin, related to Old High German 'filz' (felt), and ultimately from the Proto-Indo-European root pel- meaning "to beat" or "to thrust," referencing the process of matting fibres together to create the material. The core logic of the word's evolution lies in the material's function: from the literal substance 'felt' used for straining, the meaning generalized to any device or medium that performs a similar selective separation, whether for physical particles, light, sound, or even abstract information.
Analysis
The word 'filter' is a simplex loanword from Medieval Latin. Its spelling and form have been borrowed as a whole unit into English.
Examples
The water filter needs to be replaced every six months.
She filtered the sunlight through the thin curtains.
News about the event slowly filtered out to the public.