Source : Webster's Revised Unabridged Dictionary (1913)

Square \Square\, a.
   1. (Geom.) Having four equal sides and four right angles; as,
      a square figure.

   2. Forming a right angle; as, a square corner.

   3. Having a shape broad for the height, with rectilineal and
      angular rather than curving outlines; as, a man of a
      square frame.

   4. Exactly suitable or correspondent; true; just.

            She's a most truimphant lady, if report be square to
            her.                                  --Shak.

   5. Rendering equal justice; exact; fair; honest, as square
      dealing.

   6. Even; leaving no balance; as, to make or leave the
      accounts square.

   7. Leaving nothing; hearty; vigorous.

            By Heaven, square eaters. More meat, I say. --Beau.
                                                  & Fl.

   8. (Naut.) At right angles with the mast or the keel, and
      parallel to the horizon; -- said of the yards of a
      square-rigged vessel when they are so braced.

   Note: Square is often used in self-explaining compounds or
         combination, as in square-built, square-cornered,
         square-cut, square-nosed, etc.

   {Square foot}, an area equal to that of a square the sides of
      which are twelwe inches; 144 square inches.

   {Square knot}, a knot in which the terminal and standing
      parts are parallel to each other; a reef knot. See Illust.
      under {Knot}.

   {Square measure}, the measure of a superficies or surface
      which depends on the length and breadth taken conjointly.
      The units of square measure are squares whose sides are
      the linear measures; as, square inches, square feet,
      square meters, etc.

   {Square number}. See {square}, n., 6.

   {Square root of a number} or {quantity} (Math.), that number
      or quantity which, multiplied by itself produces the given
      number or quantity.

   {Square sail} (Naut.), a four-sided sail extended upon a yard
      suspended by the middle; sometimes, the foresail of a
      schooner set upon a yard; also, a cutter's or sloop's sail
      boomed out. See Illust. of {Sail}.

   {Square stern} (Naut.), a stern having a transom and joining
      the counter timbers at an angle, as distinguished from a
      round stern, which has no transom.

   {Three-square}, {Five-square}, etc., having three, five,
      etc., equal sides; as, a three-square file.

   {To get square with}, to get even with; to pay off. [Colloq.]

Source : WordNet®

square knot
     n : a double knot made of two half hitches and used to join the
         ends of two cords