The pivoted or swinging bar to which the traces, or tugs, of a harness are fastened, and by which a carriage, a plow, or other implement or vehicle, is drawn; a whiffletree; a swingletree; a singletree. See
Singletree. [
1913 Webster]
"[People] cut their own whippletree in the woodlot."
[1913 Webster]