noun

• (US, dialect, archaic) A barrier in a river.
  "Let him look at the plan of 1832, to which the act of 1834 refers, and upon which it is founded, and he will find that it contains detailed estimates of the expense of clearing out not only the overslaugh, but also the obstructions between Albany and Troy."
• (military, archaic) The permission to skip a duty; an exemption from an active duty.
  "When an officer is on duty he receives an "overslaugh" for all other duties that come to his turn, provided that they are not additional duties that he may be called on to perform ."

verb

• (US, dialect, slang, transitive, archaic) To hinder or stop, as by an overslaugh or impediment.
  "to overslaugh a bill in a legislative body"