It's not the only common Cyberpunk parlance to not have its origins explained, either. What the heck is "meat" damage? Why does "tracing" allow Corps to do bad stuff to the Runner? What does "link" represent? What's a "rig?" What's a "stack?" Or a "heap?"
All of these are pretty evident and commonplace to a fan of the Cyberpunk genre, as they've become staple terms and concepts.
It's also worth noting that lots of authors don't even capitalize ice anymore, and Gibson himself is the only person I can think of who published stuff that left the periods intact to make it obvious it was an acronym.
Ok, so here goes:
1. 'Meat damage' is to Meatspace as 'net damage' is to Cyberspace. It's slang for your actual, physical location, just as cyberspace is slang for the 'Net.
2. Tracing is basically a corp triangulating your meatspace location via all the LDLs or Long Distance Links (I believe, it's been a while) you've been through during your run. They 'trace' you back through the nodes you've been through back to your origin. Once they have your actual location, they can send the goons, blow up the block you're on, shut your power off, whatever.
3. A 'link' represents an LDL node, I'm guessing. Jump through enough hoops and it's harder to trace you.
4. A 'rig' is a cyberdeck, or purpose-built computer made for hacking or 'running.'
5. 'Stack' probably comes from programming code slang. I don't know enough about programming to answer this one fully.
6. 'Heap' is basically 'trash heap.'
Hope that helps