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

ACIS
       American Committee for Interoperable Systems (org., USA)


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

ACIS

    Andy, Charles, Ian's System.

   A geometric engine that most CAD packages now use.  ACIS
   uses a sophisticated object-oriented approach for modelling,
   the data is stored in boundary representation.  Acis is
   owned by Spatial Technologies.

   [How does this differ from "solid modelling"?].

   (1996-03-21)