/filˈtrāSHən/
Noun, pl. filtrations
1. Commonly the mechanical or physical operation which is used for the separation of solids from fluids (liquids or gases) by interposing a medium through which only the fluid can pass. Oversize solids in the fluid are retained, but the separation is not complete; solids will be contaminated with some fluid and filtrate will contain fine particles (depending on the pore size and filter thickness). Filtration is also used to describe some biological processes, especially in water treatment and sewage treatment in which undesirable constituents are removed by absorption into a biological film grown on or in the filter medium as in slow sand filtration. (wikipedia.org)
2. The act or process of filtering; the mechanical separation of a liquid from the undissolved particles floating in it. (wiktionary.org)
3. The movement of water and solutes across the cell membrane due to hydrostatic pressure from the cardiovascular system. (biology-online.org)
4. The process of separating suspended particles from the fluid through a porous material in which the fluid can pass while the suspended particles are retained. (biology-online.org)
5. The process whereby fluids pass through a filter or a filtering medium. (wordnetweb.princeton.edu)
Word origin: From Medieval Latin filtrum “felt,” which was used to strain impurities from liquid