The Collaborative International Dictionary of English v.0.48:

Mishap \Mis*hap"\, n.
   Evil accident; ill luck; misfortune; mischance. --Chaucer.
   [1913 Webster]

         Secure from worldly chances and mishaps. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mishap \Mis*hap"\, v. i.
   To happen unluckily; -- used impersonally. [Obs.] "If that me
   mishap." --Chaucer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mishap
    n 1: an unpredictable outcome that is unfortunate; "if I didn't
         have bad luck I wouldn't have any luck at all" [syn: bad
         luck, mischance, mishap]
    2: an instance of misfortune [syn: mishap, misadventure,
       mischance]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "mishap":
   accident, adversity, blow, calamity, casualty, cataclysm,
   catastrophe, collision, contretemps, crack-up, crash, disaster,
   dole, grief, ill hap, misadventure, mischance, misfortune,
   nasty blow, pileup, shipwreck, shock, smash, smashup,
   staggering blow, tragedy, wreck



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

MISHAP

    An early system on the IBM 1130.

   [Listed in CACM 2(5):16, May 1959].

   (2004-09-14)