pure vowel
Definition - Also called a monophthong, this is a vowel sound whose articulation at both its beginning and end is fixed, i.e. it does not move towards a new position of articulation while it is being spoken.

Example -
Some English pure vowels are:
(1) [æ] (as in bat)
(2) [ɛ] (as in bet)
(3) [ʌ] (as in but)

Etymology -
The term derives from the Greek monophthongos, single note (from monos, one + phthongos, sound or voice).

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