The Collaborative International Dictionary of English v.0.48:

Insecurity \In`se*cu"ri*ty\, n.; pl. Insecurities. [Pref. in-
   not + security : cf. LL. insecuritas, F. insecurite.]
   1. The condition or quality of being insecure; lack of
      safety; danger; hazard; as, the insecurity of a building
      liable to fire; insecurity of a debt.
      [1913 Webster]

   2. The state of feeling insecure; uncertainty; lack of
      confidence.
      [1913 Webster]

            With what insecurity of truth we ascribe effects . .
            . unto arbitrary calculations.        --Sir T.
                                                  Browne.
      [1913 Webster]

            A time of insecurity, when interests of all sorts
            become objects of speculation.        --Burke.
      [1913 Webster]

WordNet (r) 3.0 (2006):

insecurity
    n 1: the state of being subject to danger or injury [ant:
         security]
    2: the anxiety you experience when you feel vulnerable and
       insecure

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "insecurity":
   chanciness, criticalness, danger, delicacy, desultoriness,
   doubtfulness, dubiousness, hazard, hazardousness, infirmity,
   insolidity, instability, insubstantiality, peril, perilousness,
   precariousness, risk, riskiness, shakiness, shiftiness,
   shiftingness, slipperiness, speculativeness, sword of Damocles,
   ticklish business, ticklishness, totteriness, touchiness,
   treacherousness, treachery, unauthenticity, unauthoritativeness,
   uncertainty, undependability, unfaithworthiness, unhealthiness,
   unpredictability, unreliability, unsafeness, unsolidity,
   unsoundness, unsteadfastness, unsteadiness, unsubstantiality,
   unsureness, untrustworthiness