While abbreviations are useful for shortening long words, "infringement" is already fairly short and using an abbreviation might not be clear in context.
If you need a shorter way to refer to infringement, you might consider using:
* "Infringement" itself: This is often the best option for clarity.
* "IP infringement" if you are specifically referring to intellectual property infringement.
* "Copyright infringement" if you are specifically referring to copyright infringement.
* "Patent infringement" if you are specifically referring to patent infringement.
It's best to choose the abbreviation that best fits the specific context and ensures clear communication.