The Collaborative International Dictionary of English v.0.48:

Avoidance \A*void"ance\, n.
   1. The act of annulling; annulment.
      [1913 Webster]

   2. The act of becoming vacant, or the state of being vacant;
      -- specifically used for the state of a benefice becoming
      void by the death, deprivation, or resignation of the
      incumbent.
      [1913 Webster]

            Wolsey, . . . on every avoidance of St. Peter's
            chair, was sitting down therein, when suddenly some
            one or other clapped in before him.   --Fuller.
      [1913 Webster]

   3. A dismissing or a quitting; removal; withdrawal.
      [1913 Webster]

   4. The act of avoiding or shunning; keeping clear of. "The
      avoidance of pain." --Beattie.
      [1913 Webster]

   5. The courts by which anything is carried off.
      [1913 Webster]

            Avoidances and drainings of water.    --Bacon.
      [1913 Webster]

WordNet (r) 3.0 (2006):

avoidance
    n 1: deliberately avoiding; keeping away from or preventing from
         happening [syn: avoidance, turning away, shunning,
         dodging]

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "avoidance":
   Encratism, Friday, Lenten fare, Pythagoreanism, Pythagorism,
   Rechabitism, Shakerism, Spartan fare, Stoicism, abstainment,
   abstemiousness, abstention, abstinence, asceticism, banyan day,
   celibacy, chastity, continence, cringe, dodge, duck, elusion,
   eschewal, evasion, fallback, fast, fish day, flinch, fruitarianism,
   gymnosophy, nephalism, plain living, pullback, pullout, recoil,
   refraining, refrainment, retreat, runaround, sexual abstinence,
   shunning, shy, sidestep, sidestepping, simple diet, spare diet,
   teetotalism, the pledge, total abstinence, vegetarianism, wince



Bouvier's Law Dictionary, Revised 6th Ed (1856):

AVOIDANCE, eccl. law. It is when a benefice becomes vacant for want of an
incumbent; and, in this sense, it is opposed to plenarty. Avoidances are in
fact, as by the death of the incumbent or in law.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

AVOIDANCE, pleading. The introduction of new or special matter, which,
admitting the premises of the opposite party, avoids or repels his
conclusions. Gould on Pl. c. 1 Sec. 24, 42.