|1.||a porous substance, such as paper or sand, that allows fluid to pass but retains suspended solid particles: used to clean fluids or collect solid particles|
|2.||any device containing such a porous substance for separating suspensions from fluids|
|3.||any of various porous substances built into the mouth end of a cigarette or cigar for absorbing impurities such as tar|
|4.||See also band-pass filter any electronic, optical, or acoustic device that blocks signals or radiations of certain frequencies while allowing others to pass|
|5.||any transparent disc of gelatine or glass used to eliminate or reduce the intensity of given frequencies from the light leaving a lamp, entering a camera, etc|
|6.||(Brit) a traffic signal at a road junction consisting of a green arrow which when illuminated permits vehicles to turn either left or right when the main signals are red|
|—vb (foll by through)|
|8.||(tr) to obtain by filtering|
|9.||to pass (through a filter or something like a filter): dust filtered through the screen|
|10.||(intr) to flow slowly; trickle|
|[C16 filtre from Medieval Latin filtrum piece of felt used as a filter, of Germanic origin; see |
filter fil·ter (fĭl'tər)
A porous material through which a liquid or gas is passed in order to separate the fluid from suspended particulate matter.
A device containing such a substance.
Any of various electric, electronic, acoustic, or optical devices used to reject signals, vibrations, or radiations of certain frequencies while passing others.
A translucent screen, used in both diagnostic and therapeutic radiology, that permits the passage of rays having desirable levels of energy.
A device used in spectrophotometric analysis to isolate a segment of the spectrum.
To pass a liquid or gas through a filter.
To remove by passing through a filter.
To pass through or as if through a filter.
|filter (fĭl'tər) Pronunciation Key