The Collaborative International Dictionary of English v.0.48:

dependability \dependability\ n.
   the trait of being dependable or reliable.

   Syn: dependableness, reliability, reliableness.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

dependability
    n 1: the quality of being dependable or reliable [syn:
         dependability, dependableness, reliability,
         reliableness] [ant: undependability,
         undependableness, unreliability, unreliableness]

The Free On-line Dictionary of Computing (30 December 2018):

software reliability
dependability
dependable software

   See also formal methods, safety-critical system.

   (ftp://ftp.sei.cmu.edu/pub/depend-sw).  Mailing list:
   depend-sw@sei.cmu.edu.

   [Summary?]