doubletree U.S.
(ˈdʌb(ə)ltriː)
[f. double a. + tree n., after U.S. single-tree = swingle-tree.]
The cross-piece to which the swingle-tree of a carriage, plough, etc. is attached.
| 1847 [see single-tree]. 1952 Steinbeck East of Eden xiii. 121, I saw him..take the double-tree off the hay rake. |