The Collaborative International Dictionary of English v.0.48:

Cis- \Cis-\
   A Latin preposition, sometimes used as a prefix in English
   words, and signifying on this side.
   [1913 Webster]

WordNet (r) 3.0 (2006):

CIS
    n 1: an alliance made up of states that had been Soviet
         Socialist Republics in the Soviet Union prior to its
         dissolution in Dec 1991 [syn: Commonwealth of Independent
         States, CIS]

The Free On-line Dictionary of Computing (19 January 2023):

CIS

   1.  Case Integration Services.

   2.  Cooperative Information System.

   3.  Customer Interaction Software,
   Customer Information Systems.