'Swingletree' definitions:

Definition of 'swingletree'

(from WordNet)
noun
A crossbar that is attached to the traces of a draft horse and to the vehicle or implement that the horse is pulling [syn: whiffletree, whippletree, swingletree]

Definition of 'Swingletree'

From: GCIDE
  • Swingletree \Swin"gle*tree`\, n. [So named in allusion to its swinging. See Swingle, v. i., and cf. Swingtree.] A whiffletree, or whippletree. See Singletree. [1913 Webster]