Apt to break through fences. Eng. dial.

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1800.  McKinney’s horses were breachy.—Addison, ‘Law Reports,’ p. 258. (N.E.D.)

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1846.  It appeared that the gentleman from whom I had bought them was a man given to practical jokes, and had sold me a yoke of ‘breachy’ oxen, notorious for their deeds throughout the settlement.—Knick. Mag., xxviii. 343 (Oct.).

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1846.  

        Pledges air awfle breachy cattle
  Thet preudunt farmers don’t turn out,—
Ez long ’z the people git their rattle,
  Wut is there fer ’m to grout about?
Lowell, ‘Biglow Papers,’ No. 7.    

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