approximant
noun /əˈprɒksɪmənt/
  /əˈprɑːksɪmənt/
- (phonetics) a speech sound made by bringing the parts of the mouth that produce speech close together but not actually touching, for example /r/ and /w/ in right and wet in many accents of (= ways of pronouncing) English
 - (mathematics) an answer to a problem in mathematics that is a close estimate of the solution of the problem