The Collaborative International Dictionary of English v.0.48:

Isis \I"sis\, n. [L., the goddess Isis, fr. Gr. ?.]
   [1913 Webster]
   1. (Myth.) The principal goddess worshiped by the Egyptians.
      She was regarded as the mother of Horus, and the sister
      and wife of Osiris. The Egyptians adored her as the
      goddess of fecundity, and as the great benefactress of
      their country, who instructed their ancestors in the art
      of agriculture.
      [1913 Webster]

   2. (Zool.) Any coral of the genus Isis, or family Isid[ae],
      composed of joints of white, stony coral, alternating with
      flexible, horny joints. See Gorgoniacea.
      [1913 Webster]

   3. (Astron.) One of the asteroids.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Isis
    n 1: Egyptian goddess of fertility; daughter of Geb; sister and
         wife of Osiris

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "Isis":
   Amen-Ra, Anubis, Ashtoreth, Astarte, Baal, Bast, Ceres, Demeter,
   Dionysus, Frey, Horus, Khem, Min, Neph, Nephthys, Nut, Osiris, Pan,
   Priapus, Ptah, Ra, Set, Thoth



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

ISIS
       Image and Scanner Interface Specification


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

ISIS
       Industrial Signature Interoperability Specification
(cryptography)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

ISIS
       Integrated Systems and Information Services (OS, Intel)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

ISIS
       Intermediate System to Intermediate System [protocol / routing]
(OSI, RFC 1195), "IS-IS"


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

ISIS

   1. A toolkit for implementing fault-tolerant distributed
   systems, developed at Cornell and now available commercially

   2. A dialect of JOSS.

   [Sammet 1969, p. 217].