(n) :
a
vowel (in the sense of a sound rather than a letter of the alphabet) that has the same sound throughout its pronunciation, such as the short vowels in "pap", "pep", "pip", "pop" and "pup", as opposed to a
diphthong (eg, /a?/, the vowel in "pipe") or a
triphthong (eg, /a??/, the sound in the
non-rhotic pronunciation of "pyre")