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
    Jun 4 '15 at 3:23
  • Good question, I've always wondered this too.
    – Caleb
    Jul 9 '15 at 23:40

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
    May 23 '14 at 13:54
  • This is ridiculous. "Proc" has been used in computing since the 50s.
    – Hot Licks
    Sep 20 '20 at 20:45
  • 1
    @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
    Sep 21 '20 at 3:55

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.

  • 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. Jun 4 '15 at 10:37

"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
    May 23 '14 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
    May 23 '14 at 13:57
  • 3
    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
    May 31 '14 at 1:52
  • 1
    "No one uses proc to describe events that are expected to be certain." Actually, they do quite frequently.
    – MrHen
    Jun 5 '14 at 15:30
  • 1
    I agree with Patrick, this particular bit of lore seems like a backronym rather than the real origin of this term.
    – herisson
    Jun 4 '15 at 3:07

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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