'Doubletree' definitions:
Definition of 'doubletree'
From: WordNet
noun
A crossbar on a wagon or carriage to which two whiffletrees are attached in order to harness two horses abreast
Definition of 'Doubletree'
From: GCIDE
- Doubletree \Dou"ble*tree`\, n. The bar, or crosspiece, of a carriage, to which the singletrees are attached. [1913 Webster]