A list of 9,123 English monosyllables published in 1957 includes three ten-letter words: scraunched, scroonched, and squirreled.
Some candidates are questionable on grounds of spelling, pronunciation, or status as obsolete, nonstandard, proper noun, loanword, or nonce word.
Thus, the definition of longest English word with one syllable is somewhat subjective, and there is no single unambiguously correct answer.
Some nine-letter proper names remain monosyllabic when adding a tenth letter and apostrophe to form the possessive: In his short story, "Strychnine in the Soup", P. G. Wodehouse had a character whose surname was "Mapledurham", pronounced "Mum".
Attested examples include scratch'dst[18] and stretch'dst,[19] each of which has one syllable spelled with ten letters plus apostrophe.