D defs.my
Entry 1 sense Webster, 1913

Doubletree

/dŭb'-əl-trēˌ/ · Dou·ble·tree · IPA /dˈʌbəltrˌiː/
01 n. The bar, or crosspiece, of a carriage, to which the singletrees are attached.
  1. 1.
    The bar, or crosspiece, of a carriage, to which the singletrees are attached.