(phonetics) an individual sound unit of speech without concern as to whether or not it is a phoneme of some language

a vowel whose quality or length is changed to indicate linguistic distinctions (such as sing sang sung song)

a vowel sound that starts near the articulatory position for one vowel and moves toward the position for another

a neutral middle vowel; occurs in unstressed syllables

a vowel that ends a stem and precedes an inflection

a vowel prefixed or a lengthening of the initial vowel to mark past time especially in Greek and Sanskrit verbs.