The word is PC.
a computer designed for use by one person at a time.
A desktop is a PC.
A desktop computer is a personal computer designed for regular use at a single location on or near a desk or table due to its size and power requirements.
A laptop is a PC.
- a personal computer that is small and light enough to be operated on the user's lap Compare palmtop computer
A Mac is a PC (sorry but it's true).
a compact computer that uses a microprocessor and is designed for individual use, as by a person in an office or at home or school, for such applications as word processing, data management, financial analysis, or computer games.
In early 1977, they founded Apple Computer which quickly became one of the dominant forces in the personal-computer field.
From the Archives: Steve Jobs on the Birth of the Mac
October 5, 2011
When people say Mac vs. PC they're really saying Mac vs. Not Mac.
PC, or personal computer, is a generic term. No one owns it. Thus it can suffer from a lack of promotion.
Every desktop and laptop Apple has ever produced has been a PC. They didn't all use the same CPU or operating system as the IBM clone PC that still dominates the market share but they were all personal computers.
Why doesn't everyone know this? Because Apple spent a lot of money convincing people they weren't just buying an overpriced PC.
For a long time Apple used motorola CPU's that were not compatible with intel/amd x86 CPU's used to make clones of IBM's PC. Thus Apple PC's were not compatible with the windows operating system and couldn't run it's applications without emulation.
Since Apple was the only one making these motorola computers if you didn't call them Apple or Mac computers but simply PC people would assume you meant the x86 based ones based on context since IBM clone PC is a mouthful.
But now Apple uses intel to make it's PC's so you can't say there is any difference other than branding. You can install windows on an Apple PC and it will run natively, without emulation.
So PC means personal computer. This can include Apple PCs or not depending on how you use it. You don't have to take my word for it, this has already been asked here before: Is it correct to call an Apple Mac computer a PC (Personal Computer)
Not all PCs are Macs, but all Macs are PCs.
Anyway, here's how I'd word it:
I am creating an app which is intended for use on PCs running unix, windows, or OSX.
Or more ambitiously:
I am creating an app which is intended for use on PCs running any operating system.
If you can pull that off without fragmenting your code base I'd love to know how. And don't say Java.