verb

• (ambitransitive) To reach above or beyond, especially to an excessive degree.
  "[...] I cannot forget what the poet Martial saith; "O quantum est subitis casibus ingenium!" signifying, that accident is many times more subtle than foresight, and overreacheth expectation; [...]"
• (ambitransitive) To reach above or beyond, especially to an excessive degree.
  "[A]n equitable mortgage, by deposit of deeds to a person, bona fide, and without notice, will give him a preferable equity; and will overreach the vendor's equitable lien on the estate for any part of the purchase-money."
• (ambitransitive, figuratively) To do something beyond an appropriate limit, or beyond one's ability; to overextend.
  "The British Empire would not have endured so long had it not been for a discreet sense of moderation in its rulers, generation after generation. The coolness displayed towards the colonies by successive British Governments has at least prevented the empire-builders from overreaching themselves."
• (ambitransitive, reflexive, equestrianism) Of a horse: to strike the heel of a forefoot with the toe of a hindfoot.
  "Attinto, [...] Alſo when a horſe is tainted or hurt, or ouerreacheth one foote with another, and withal doth hurt a ſinew."

noun

• (also figuratively) An act of extending or reaching over, especially if too far or too much; overextension.
  "It may not be much of a stretch to say that there had always been something comforting about the earlier periods of judicial activism. [...] Ideology aside, one may concede that such Supreme Court activism was far less frightening in its institutional overreach than a wholesale creation of new and public law by the judicial branch would be."
• (equestrianism) Of a horse: an act of striking the heel of a forefoot with the toe of a hindfoot; an injury caused by this action.
  "The hunter's [i.e., hunting horse's] legs should be washed with warm water, carefully examined for thorns, overreaches, &c., and the legs should be rubbed dry, and well hand rubbed, by which means a free circulation of the blood will be promoted."