doubletree

(-trē′)

☆

noun

a crossbar on a wagon, carriage, plow, etc., to each end of which the singletrees are attached when two horses are harnessed abreast

Origin: double + (single)tree

See doubletree in American Heritage Dictionary 4

noun

A crossbar on a wagon or carriage to which two whiffletrees are attached for harnessing two animals abreast.

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