nonsyllabic
adjective()
not forming a syllable or the nucleus of a syllable; consisting of a consonant sound accompanied in the same syllable by a vowel sound or consisting of a vowel sound dominated by other vowel sounds in a syllable (as the second vowel in a falling diphthong)
Examples:
The nonsyllabic `n' in `botany' when it is pronounced `botny'.
The nonsyllabic `i' in `oi'.