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

Targa Graphics Adaptor
TGA

    (TGA) The Truevision Targa Graphics
   Adaptor file format.

   The TGA format is a common bitmap file format for storage of
   24-bit images.  It supports colourmaps, alpha channels,
   compression and comments.

   Filename extension: .tga.

   More information is available from
   Truevision (http://truevision.com/) and
   The Graphics File Format Page
   (http://dcs.ed.ac.uk/~mxr/gfx/).

   [What does it have to do with graphics adaptors?]

   (1997-08-07)