Definition of doubletree in English:

doubletree

noun

North American
  • A crossbar in front of a wagon with a swingletree at each end, enabling two horses to be harnessed.

    • ‘The doubletree on the wagon could be adjusted to allow one horse to pull more.’
    • ‘The wheel horses pull on the doubletree against this hammerpin running through the wagon-tonque.’

Origin

Mid 19th century: from double, on the pattern of singletree.

Pronunciation:

doubletree

/ˈdəbəlˌtrē/