Filter - philtre

From Hull AWE
Jump to: navigation, search

Filter and philtre form one of the sets of homophones listed by the then Poet Laureate Robert Bridges.
(For more, see Bridges homophones). AWE has a category listing our articles on each of these.

Although filter has been spelled philter in the past, this would now be judged wrong. Distinguish between them.

  • The noun 'a filter' and the associated verb 'to filter' are centrally about the process of removing solid matter from a liquid, or (later) a gas. The terms have been expanded in many directions: filter rules in some disciplines are methods of exluding certain phenomena from discussion; sound filters exclude unwanted noises freom recordings - or indeed the ears; photographic filters exclude light of certain wavelengths from observation, or photographs; the filters in some cigarettes intercept some noxious matter from being inhaled; air filters remove unwanted matter (usually solid) from air being introduced to engines, buildings and so on. Many face masks, patticularly in medical use, include filters as part of their protection.
  • The noun 'a philtre' is archaic. It means 'a magic potion [particularly for exciting love or sexual desire]'. This spelling should only be used in historical contexts - it does NOT an alternative spelling for 'filter'.