A river, mostly in Devon, England, rising in Exmoor and flowing into the English Channel near Exmouth
"She signed her business card with her name and the initials A.B.C., exe to indicate she was an alumnus of the University of Exeter."
University of Exeter, used especially following post-nominal letters indicating status as a graduate.
Exe is a shortened form of the word executable that entered common usage as a file extension. It was clipped from the longer term to provide a quick way to identify computer programs.