Definition of filter noun from the Oxford Advanced Learner's Dictionary



    BrE BrE//ˈfɪltə(r)//
    ; NAmE NAmE//ˈfɪltər//
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  1. 1a device containing paper, sand, chemicals, etc. that a liquid or gas is passed through in order to remove any materials that are not wanted an air/oil filter a coffee/water filter filter paper for the coffee machine He smokes cigarettes without filters.
  2. 2a device that allows only particular types of light or sound to pass through it The camera has an anti-glare filter.
  3. 3(computing) a program that processes information to exclude the types which are not wanted or that stops certain types of electronic information, email, etc. being sent to a computer See related entries: Email
  4. 4(British English) a light on a set of traffic lights showing that traffic can turn left or right while traffic that wants to go straight ahead must wait a filter lane
  5. Word Originlate Middle English (denoting a piece of felt): from French filtre, from medieval Latin filtrum ‘felt used as a filter’, of West Germanic origin and related to felt.
See the Oxford Advanced American Dictionary entry: filter