The Collaborative International Dictionary of English v.0.48:

Square \Square\, v. t. [imp. & p. p. Squared (skw[^a]rd); p.
   pr. & vb. n. Squaring.] [Cf. OF. escarrer, esquarrer. See
   Square, n.]
   1. To form with four equal sides and four right angles.
      --Spenser.
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   2. To form with right angles and straight lines, or flat
      surfaces; as, to square masons' work.
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   3. To compare with, or reduce to, any given measure or
      standard. --Shak.
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   4. To adjust; to regulate; to mold; to shape; to fit; as, to
      square our actions by the opinions of others.
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            Square my trial
            To my proportioned strength.          --Milton.
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   5. To make even, so as to leave no remainder or difference;
      to balance; as, to square accounts.
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   6. (Math.) To multiply by itself; as, to square a number or a
      quantity.
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   7. (Astrol.) To hold a quartile position respecting.
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            The icy Goat and Crab that square the Scales.
                                                  --Creech.
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   8. (Naut.) To place at right angles with the keel; as, to
      square the yards.
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   To square one's shoulders, to raise the shoulders so as to
      give them a square appearance, -- a movement expressing
      contempt or dislike. --Sir W. Scott.

   To square the circle (Math.), to determine the exact
      contents of a circle in square measure. The solution of
      this famous problem is now generally admitted to be
      impossible.
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WordNet (r) 3.0 (2006):

squared
    adj 1: having been made square