WordWeb Online

1. 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 unsyllabic 'n' in 'botany' when it is pronounced 'botny'";
   - nonsyllabic

See also: unsyllabled