The Collaborative International Dictionary of English v.0.48:

Acroceraunian \Ac`ro*ce*rau"ni*an\, a. [L. acroceraunius, fr.
   Gr. ? high, n. pl. ? heights + ? thunderbolt.]
   Of or pertaining to the high mountain range of
   "thunder-smitten" peaks (now Kimara), between Epirus and
   Macedonia. --Shelley.
   [1913 Webster]