I just ran some code over the CMU pronouncing dictionary and the longest words identified as single-syllable that are English-origin and not proper names or possessives were
The CMU dictionary thinks that "scrambled" is two syllables as a vowel ends up between the "b" and the "l" in pronunciation. Wiktionary thinks this is a syllabic l (/l̩/), which should probably be counted as a separate syllable even if it isn't considered a vowel.
Wikipedia says
> Many dialects of English may use syllabic consonants in words such as even [ˈiːvn̩], awful [ˈɔːfɫ̩] and rhythm [ˈɹɪðm̩], which English dictionaries' respelling systems usually treat as realizations of underlying sequences of schwa and a consonant (for example, /ˈiːvən/).
That's consistent with what the CMU dictionary is doing, perhaps treating /l̩/ as /əl/.
I just ran some code over the CMU pronouncing dictionary and the longest words identified as single-syllable that are English-origin and not proper names or possessives were
For eight letters, it found dozens of examples!
The CMU dictionary thinks that "scrambled" is two syllables as a vowel ends up between the "b" and the "l" in pronunciation. Wiktionary thinks this is a syllabic l (/l̩/), which should probably be counted as a separate syllable even if it isn't considered a vowel.
Wikipedia says
> Many dialects of English may use syllabic consonants in words such as even [ˈiːvn̩], awful [ˈɔːfɫ̩] and rhythm [ˈɹɪðm̩], which English dictionaries' respelling systems usually treat as realizations of underlying sequences of schwa and a consonant (for example, /ˈiːvən/).
That's consistent with what the CMU dictionary is doing, perhaps treating /l̩/ as /əl/.