"RAW" has the same meaning of "raw" such as in "raw vegetables," and is not an abbreviation like JPEG (Joint Photographic Experts Group).
Digital cameras generally perform digital processing to the output signals from image sensor, and create JPEG images. Meanwhile, RAW is a data format whose processing parameters can be adjusted freely by photographers.
NOTE: RAW data taken with Sony cameras are saved with an extension "ARW".
Frequently Asked Questions about RAW file
Imaging Edge Desktop (Image Data Converter successor)