I feel like I used to know the answer to this...
In classic Mac days, probably the early 90s and before, some applications would have a cursive / decorative ƒ character in their names.
What was the significance of this?
It wasn’t typically in the application’s name, it was in the name of the folder containing the application, and used to mean “folder.”
For example, the folder containing SurfWriter, its Apple Guide help file, its template files, and so on may have been named “SurfWriter ƒ” either by the developer or by a user.
Often developers named the folder something like “SurfWriter 1.0.5 Folder” and a user would change it to “SurfWriter ƒ” to make things line up more easily, but still return a distinguishable result when searching their disk.