The word "proc" is used to describe an event that occurs at various intervals and seems to be a term unique to programming and gaming:

When does that event proc?

If that trigger procs it will cause [...]

This card has an ability that procs when you play [...]

When the card proc'ed/procced, it killed off all opposing creatures and won me the game.

The word does not appear in the dictionaries I checked. "Proc" is listed as an abbreviation for words like "proceeding":


  1. procedure
  2. proceedings
  3. process
  4. proclamation
  5. proctor

But these seem completely unrelated to the usage I've noted above. So where did this term originate?

  • 3
    In general, in computing, "proc" is short for either "procedure" or "process". There may of course be other things it means in special contexts (such as gaming), but those meanings would not be known to a computer programmer who was not familiar with those contexts.
    – Hot Licks
    Commented Jun 4, 2015 at 3:23
  • Good question, I've always wondered this too.
    – Caleb
    Commented Jul 9, 2015 at 23:40

4 Answers 4


According to this article from 2006, proc comes from way back in the old MUD (multi-user dungeon) days, although it didn't get popularized until Everquest.

Short for spec_proc (special procedure), which is a bit of code triggered to cover a special case that the default code doesn’t handle.

In the older muds there was almost no variation between what a given object could do. For example all weapons used the weapon type, then you could specify damage type (was it a sword or a mace), damage ranges, and so on.

To get the weapon to do anything special, you had limited choices. Depending on the architecture, you could attach a spell to be cast, or could attach a script if the code supported it. In the codebases that Brad & co. played, the devs could not script, so the codebase allowed a pointer to a special hardcoded procedure to be entered in the weapon data.

“Proc” is almost entirely EQ slang… Even in the muds, it wasn’t that widely used because only some codebases used the term. It took EQ publicizing the inherited term to make it common knowledge.

  • This origin seems to match the usage most accurately. Whenever I do searches for "proc" I constantly hit abbreviated form for "procedure". It makes search for this particular usage nearly impossible but does it does lend weight to the theory that "proc" originated from a specific usage of "procedure."
    – MrHen
    Commented May 23, 2014 at 13:54
  • This is ridiculous. "Proc" has been used in computing since the 50s.
    – Hot Licks
    Commented Sep 20, 2020 at 20:45
  • 4
    @HotLicks - As a verb? I’ve only been programming since the late 70’s but I’ve never encountered “When does that event proc” or “If that trigger procs it will cause...”
    – Jim
    Commented Sep 21, 2020 at 3:55

"proc" comes from "Programmed Random Occurrence," at least according to some variants of programming lore.


  • It seems likely that PROC morphed into how we use "proc" today but the modern term does not require a randomness factor. Something that triggers 100% of the time still "procs".
    – MrHen
    Commented May 23, 2014 at 13:55
  • 1
    @mrhen that seems to be an effect of the word being used to describe chance events, and those chance events evolving to become certain. No one uses proc to describe events that are expected to be certain. The sun rising isn't ever a proc.
    – Emily
    Commented May 23, 2014 at 13:57
  • 5
    This seems like a backronym. It seems rare in my experience that people take anything other than the first letters of the words involved except to make a backronym. It's useful to know that many people and sources will cite this as the meaning, but I've come to believe it was added after the fact.
    – Patrick
    Commented May 31, 2014 at 1:52
  • 1
    "No one uses proc to describe events that are expected to be certain." Actually, they do quite frequently.
    – MrHen
    Commented Jun 5, 2014 at 15:30
  • 2
    I agree with Patrick, this particular bit of lore seems like a backronym rather than the real origin of this term.
    – herisson
    Commented Jun 4, 2015 at 3:07

Its used in exactly the same way as spawn. Both mean something has triggered. I find spawn to be a little easier to understand, however, as it's a real word.

  • 1
    Thank you for taking the time to answer. I would find this more convincing if you could show how spawn can be used in the example situations in the question. Commented Jun 4, 2015 at 10:37

I've played computer games longer than I'd like to admit, and I think the term is an abbreviation of:

percentage occurence

For example, if an action was to happen 20% of the time, we'd say it procs once in a five.

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