The Collaborative International Dictionary of English v.0.48:

Reliability \Re*li`a*bil"i*ty\ (r?-l?`?-b?l"?-t?), n.
   The state or quality of being reliable; reliableness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "reliability":
   acceptability, aplomb, authenticity, authoritativeness, balance,
   balanced personality, believability, believableness, calculability,
   conceivability, constancy, cool, credibility, credit,
   dependability, equilibrium, faithworthiness, fastness, firmness,
   homeostasis, imperturbability, incorruptibility, invariability,
   invincibility, inviolability, nerve, plausibility, predictability,
   responsibility, rootedness, sang-froid, secureness, security,
   solidity, soundness, stability, stable equilibrium, stable state,
   staunchness, steadfastness, steadiness, steady nerves,
   steady state, substantiality, sureness, tenability, trustability,
   trustiness, trustworthiness, undeflectability, unerringness,
   unfalseness, uniformity, unperfidiousness, unshakable nerves,
   unshakableness, untreacherousness, validity



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

reliability

    An attribute of any system that consistently produces
   the same results, preferably meeting or exceeding its
   specifications.  The term may be qualified, e.g software
   reliability, reliable communication.

   Reliability is one component of RAS.

   (2000-08-13)