a virus particle small enough to pass through a filter of diatomaceous earth or porcelain, which will not pass bacteria: chiefly historical or an informal indicator of size, as synthetic membrane filters now permit passage of the smallest virus.
noun 1. a pond or tank having a false bottom covered with sand and serving to filter river or pond waters. noun 1. a layer of sand or gravel in a tank or reservoir through which a liquid is passed so as to purify it Compare bacteria bed 2. any layer of material through which […]
- Filter cake
noun 1. (chem) the solid material accumulated by a filter press
[fil-ter] /ˈfɪl tər/ noun 1. any substance, as cloth, paper, porous porcelain, or a layer of charcoal or sand, through which liquid or gas is passed to remove suspended impurities or to recover solids. 2. any device, as a tank or tube, containing such a substance for filtering. 3. any of various analogous devices, as […]
noun, Photography. 1. a number indicating the increased exposure that a particular film should receive when a photograph is taken using a particular filter.