We don't have synonyms for monowheel yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are tonewheel.
°A vehicle similar to a unicycle, its rider sitting within or adjacent to the single wheel.
"We had bought the monowheel at Portal, where it had been left for sale by an absent missionary; it was a single bicycle wheel with a seat arranged on it... — Mary Hastings Bradley, Caravans and Cannibals (1926)"
°A vehicle similar to a unicycle, its rider sitting within or adjacent to the single wheel.
"We had bought the monowheel at Portal, where it had been left for sale by an absent missionary; it was a single bicycle wheel with a seat arranged on it... — Mary Hastings Bradley, Caravans and Cannibals (1926)"