In many questions and answers on league of legends, I see people refers to "proc" or "procing" like :

I don't agree with the use of the term. The meaning I found long time ago and seems backed up by : http://www.internetslang.com/PROC-meaning-definition.asp and http://www.wowwiki.com/Proc is that PROc means Programmed Random Occurrence.

Even if the last article says it's debatable, it is obvious that it refers to "Chances on hit/spells".

All of this to say that Spell Vamp (for example) in LoL is a "on hit effect" with no relation to chances at all. On the contrary "Madred's Razors" have a "15% chance on hitting a minion or monster to deal 500 bonus magic damage.". So Madred's Razor damages can proc unlike "Rilay scepter" slow that just applies for each hits.

The LoL wikia seems also to do extensive use of the word "proc" as a synonym of "on hit effect". Even the 'proc' page is redirected there.

So my question is :

  • should we change all of this to a correct formulation ? (I don't want to start a edit frenzy)
  • should I just stand back and suffer in silence at that semantic horror and try to keep telling me that a 100% chance on hit effect is still a programmed random occurrence?
  • Am I wrong?
  • Edit away to your heart's content, just do avoid edit wars and flooding the homepage with one-word edits. If the author rolls you back, do not insist.
    – badp
    Mar 27, 2012 at 9:57
  • 9
    Oh yay, now we get fight about the contentious etymology of Proc. (Nobody is able to confirm whether the backronym or spec_proc came first, and both definitions are widely distributed.) The point is, language is a living thing, and Proc is widely used to mean 'effect which is triggered by an item', and it makes complete sense in context to anyone who is part of the community. There's no reason to succumb to pedantry in this case. Yes, even I am rejecting pedantry here. Mar 27, 2012 at 14:01
  • That's why I preferred to ask first. I'll let this be then I guess. Just wanted to know what other thought of it.
    – M'vy
    Mar 27, 2012 at 15:38

2 Answers 2


It might be because you have misunderstood the meaning of Proc, if you read the history on the WoWWiki you linked to you will see that it says:

Proc was originally short for "spec_proc" (spec_proc is short for "special procedure") which is a term used by the original programmer of Circle-MUD, Jeremy Elson. It might have been used as well by the original programmers of diku-MUD as well. Special procedures in Circle-MUD are functions that can be assigned to objects, players, and locations in the world such that each time an event occurs, the special procedure function will be invoked.

So proc applies to events that has 100% chance of happening as long as it is an additional procedure that is evoked once an event happens like spell vamp in LoL.

  • So, suppose you have 2 swords that are functionally the same, but one has an attached procedure that runs on each successful hit, while the other has an attribute that is passed to a procedure that runs on a successful hit with any weapon. Does that mean the first sword "procs" while the other doesn't?
    – kotekzot
    Apr 17, 2012 at 7:44
  • @kotekzot No, proc do not have to be tied directly to the weapon, some games have abilities/talents that enable procs from weapons. In the case you suggested it would most likely just mean that the first sword can proc two events and the second could proc one.
    – Blem
    Apr 17, 2012 at 9:22

Programmed Random OCcurence is a backronym, and like most backronyms it doesn't really fit properly.

Typically the term is used for abilities which have a chance of happening, but the usage of the term for one thing calling another procedure is correct from a programmatic point of view.

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