an individual vowel articulated without change in quality through the entire length of a syllable, since the vowel of English sleep.
Two written vowels representing just one sound, as oa in boat.
A vowel (into the feeling of a sound versus a letter of this alphabet) with the same sound throughout its pronunciation, for instance the brief vowels in "pap", "pep", "pip", "pop" and "pup", rather than a diphthong (eg, /aɪ/, the vowel in "pipe") or a triphthong (eg, /aɪə/, the sound when you look at the non-rhotic pronunciation of "pyre").
just one uncompounded vowel sound.
a mix of two written vowels pronounced together; a digraph.
A simple vowel-sound.
a variety of two written vowels pronounced as one.