CATIA is an abbreviation. Dassault Systèmes describes it as a widely used software suite for CAD, CAM and CAE.
CATIA V5 stands for Computer-Aided Three-dimensional Interactive Application V5. Dassault Systèmes describes it as a widely used software suite for CAD (design), CAM (manufacturing) and CAE (engineering analysis).
The official page mentions industries such as automotive, aerospace and industrial equipment.
Source: CATIA V5, Dassault Systèmes