The Collaborative International Dictionary of English v.0.48:

Security \Se*cu"ri*ty\, n.; pl. Securities. [L. securitas: cf.
   F. s['e]curit['e]. See Secure, and cf. Surety.]
   1. The condition or quality of being secure; secureness.
      Specifically:
      (a) Freedom from apprehension, anxiety, or care;
          confidence of power or safety; hence, assurance;
          certainty.
          [1913 Webster]

                His trembling hand had lost the ease,
                Which marks security to please.   --Sir W.
                                                  Scott.
          [1913 Webster]
      (b) Hence, carelessness; negligence; heedlessness.
          [1913 Webster]

                He means, my lord, that we are too remiss,
                Whilst Bolingbroke, through our security,
                Grows strong and great in substance and in
                power.                            --Shak.
          [1913 Webster]
      (c) Freedom from risk; safety.
          [1913 Webster]

                Give up yourself merely to chance and hazard,
                From firm security.               --Shak.
          [1913 Webster]

                Some . . . alleged that we should have no
                security for our trade.           --Swift.
          [1913 Webster]

   2. That which secures or makes safe; protection; guard;
      defense. Specifically:
      (a) Something given, deposited, or pledged, to make
          certain the fulfillment of an obligation, the
          performance of a contract, the payment of a debt, or
          the like; surety; pledge.
          [1913 Webster]

                Those who lent him money lent it on no security
                but his bare word.                --Macaulay.
          [1913 Webster]
      (b) One who becomes surety for another, or engages himself
          for the performance of another's obligation.
          [1913 Webster]

   3. An evidence of debt or of property, as a bond, a
      certificate of stock, etc.; as, government securities.
      [1913 Webster]

   Syn: Protection; defense; guard; shelter; safety; certainty;
        ease; assurance; carelessness; confidence; surety;
        pledge; bail.
        [1913 Webster]