invariability
  不變,不變性,安定性
  In·va·ri·a·bil·i·ty n.  The quality of being invariable; invariableness; constancy; uniformity.
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  invariability
       n 1: a quality of uniformity and lack of variation [syn: evenness]
            [ant: unevenness, unevenness]
       2: the quality of being resistant to variation [syn: invariableness,
           invariance] [ant: variability, variability]