What does filtration mean?
Filtration is the process of separating solid particles from a liquid or gas by forcing the fluid through a filter or other porous material that traps unwanted matter while letting the clarified fluid pass through. The word belongs chiefly to scientific and technical registers: chemists speak of gravity and vacuum filtration, engineers design water and air filtration systems, and physicians monitor kidney health through the glomerular filtration rate. Beyond the laboratory, filtration also carries a figurative sense — the selective screening of information, content, or people, as in the filtration of internet traffic or of job applicants. It derives from the Latin filt rum, meaning a piece of felt, which was used historically to strain liquids; this makes the word a small piece of material history preserved in modern usage. Reliable, practical, and quietly essential, filtration names one of the fundamental operations on which clean water, safe air, and many industrial processes depend.
The process of passing a liquid or gas through a filter to remove suspended particles or impurities.
"Clarification of the extract was achieved by filtration through activated charcoal."
In scientific contexts, filtration is typically modified by technique or medium, e.g., vacuum filtration or membrane filtration.
More broadly, the act or result of filtering something, including selective restriction of information or access.
"Public complaints led to tighter filtration of comments on the forum."
The plural is rare and mainly confined to technical or laboratory contexts referring to multiple distinct instances of the procedure.
"Three separate filtrations were performed before the solution reached the required purity."
Your kidneys perform glomerular filtration about 180 litres of blood plasma every day — roughly enough to fill a bathtub twice — yet you excrete only about two litres as urine.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of filtration
Filtration comes from the Medieval Latin filtratio, derived from filtrare, 'to filter', which itself traces back to filt rum, the Latin word for a piece of felt. Felt was commonly used to strain liquids in pre-modern practice, so the term literally preserves the memory of cloth doing the work now done by paper, membranes, and ceramics. English adopted both the verb 'filter' and the noun 'filtration' from French and Late Latin sources, with 'filtration' attested by the early seventeenth century. Cognates include 'filtrate' and 'infiltrate', all sharing the same felt-based root.
How filtration is actually used
Filtration is a formal-to-neutral noun common in scientific, medical, and technical writing. In chemistry it is often qualified by method (gravity, vacuum, membrane, ultrafiltration). In medicine, phrases such as 'glomerular filtration rate' are standard. Figurative uses (e.g., 'filtration of information') are understood but less frequent than the literal sense.
Easily confused with filtration
Distillation purifies a liquid by boiling it and condensing the vapour, whereas filtration removes particles by passing the liquid through a filter without changing its state.