precondition

from WordNet (r) 3.0 (2006)

precondition
    n 1: an assumption on which rests the validity or effect of
         something else [syn: {condition}, {precondition},
         {stipulation}]
    2: an assumption that is taken for granted [syn: {given},
       {presumption}, {precondition}]
    3: a condition that is a prerequisite
    v 1: put into the required condition beforehand

from The Collaborative International Dictionary of English v.0.48

Precondition \Pre`con*di"tion\, n.
   A previous or antecedent condition; a preliminary condition.
   [1913 Webster]