A monosyllabic word has just one syllable. And while plenty of monosyllabic words exist, the longest ones all happen to start with the letter “s” according to Guinness World Records. At 10 letters, “scraunched” and “strengthed” are the longest monosyllabic words in the English language. “Screeched,” “scrounged,” “squelched,” “straights,” and “strengths” come in second place with nine letters each.