Source : Webster's Revised Unabridged Dictionary (1913)

   {To knock off}, to cease, as from work; to desist.

   {To knock under}, to yield; to submit; to acknowledge one's
      self conquered; -- an expression probably borrowed from
      the practice of knocking under the table with the
      knuckles, when conquered. ``Colonel Esmond knocked under
      to his fate.'' --Thackeray.

Knock \Knock\ (n[o^]k), v. t.
   1. To strike with something hard or heavy; to move by
      striking; to drive (a thing) against something; as, to
      knock a ball with a bat; to knock the head against a post;
      to knock a lamp off the table.

            When heroes knock their knotty heads together.
                                                  --Rowe.

   2. To strike for admittance; to rap upon, as a door.

            Master, knock the door hard.          --Shak.

   {To knock down}.
      (a) To strike down; to fell; to prostrate by a blow or by
          blows; as, to knock down an assailant.
      (b) To assign to a bidder at an auction, by a blow or
          knock; to knock off.

   {To knock in the head}, or {on the head}, to stun or kill by
      a blow upon the head; hence, to put am end to; to defeat,
      as a scheme or project; to frustrate; to quash. [Colloq.]
      -- {To knock off}.
      (a) To force off by a blow or by beating.
      (b) To assign to a bidder at an auction, by a blow on the
          counter.
      (c) To leave off (work, etc.). [Colloq.] -- {To knock
   out}, to force out by a blow or by blows; as, to knock out
      the brains.

   {To knock up}.
      (a) To arouse by knocking.
      (b) To beat or tire out; to fatigue till unable to do
          more; as, the men were entirely knocked up. [Colloq.]
          ``The day being exceedingly hot, the want of food had
          knocked up my followers.'' --Petherick.
      (c) (Bookbinding) To make even at the edges, or to shape
          into book form, as printed sheets.