"unsyllabic" in the adjective sense
1. nonsyllabic, unsyllabic
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
"the nonsyllabic `n' in `botany' when it is pronounced `botny'"
"the nonsyllabic `i' in `oi'"
Source: WordNet® (An amazing lexical database of English)
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