transitive. To detach (horses) from a cart.

To free (horses, etc.) from harness; to unyoke. Also figurative and (in later use) absol.

(un-, prefix2 affix 1a + span, v.2 Cf. Old English un-, onspannan, Dutch ontspannen.)

To unharness the horses from (a carriage, etc.).

transitive. To unyoke or unhitch (oxen or other draught animals) from a wagon or plough. Also: to unhitch (a wagon) from its draught animals. Now…

To disconnect (the plough) from a draught-animal. Also in figurative context.