In programming and logic, for example, the "or" is meaning something that may or may not be added to the previous or afterwards: A or B (A only; B only; A and B).

However, in real live conversations it's usually not the case. If someone says A or B, they will probably mean: A without B; B without A.

I search it and couldn't find the proof for this. Can someone help to point this out: what is the real meaning of the "or" in grammar. Is it the first case or the second?

Please provide some links(references) or whatever to back your opinion.

  • "In programming and logic, for example, the "or" is meaning something ..." -- wrong. There are several kinds of "OR" in programming and logic. The question is based on an incorrect premise and on oversimplification.
    – Kris
    Commented Nov 2, 2018 at 8:03
  • Kris, what do you mean by several kinds of "OR" in programming?
    – tiju
    Commented Nov 2, 2018 at 8:11
  • That one needs to research and find out before posting a question here, as a pre-requisite. Please read the FAQ.
    – Kris
    Commented Nov 2, 2018 at 8:18
  • Kris, what make you think I didn't - if I don't know it, it doesn't mean I didn't "research" it.
    – tiju
    Commented Nov 2, 2018 at 8:30
  • tiju, just show something to convince people here that you tried -- that's required by all of us according to the FAQ. Also, do you know that you can quickly earn some points just by reading the FAQ section? Good Luck.
    – Kris
    Commented Nov 2, 2018 at 8:40

1 Answer 1


Context will normally determine if it's the inclusive or exclusive or that's meant.

Barring that, it needs to be specified if there is room for ambiguity and it makes a difference.


Do A or B or both.
Do A or B or both A and B.


Do only A or B.
Do A or B, but not both.

From Wikipedia:

Natural language

As with other notions formalized in mathematical logic, the meaning of the natural-language coordinating conjunction or is closely related to but different from the logical or. For example, "Please ring me or send an email" likely means "do one or the other, but not both". On the other hand, "Her grades are so good that either she's very bright or she studies hard" does not exclude the possibility of both. In other words, in ordinary language "or" (even if used with "either") can mean either the inclusive "or" [inclusive-]or the exclusive "or."

  • +1, mainly for understanding the question. Commented Nov 2, 2018 at 7:37
  • But wait. See my comment at OP.
    – Kris
    Commented Nov 2, 2018 at 8:04
  • Thank you Jason. So basically the context is what determine if there's silent "only" in the sentence, even if there's no actual "only" word there.
    – tiju
    Commented Nov 2, 2018 at 8:14
  • @tiju Normally, you can make a good guess from the rest of the sentence. In some cases, it doesn't matter if it's interpreted as inclusive or exclusive—it won't change the result. (The first example in the text I quoted, "please ring me or send an email," is a good example. It would normally be interpreted as exclusive—but even if the person did both things, it would still serve the purpose of getting the other person's attention.) Commented Nov 2, 2018 at 8:23
  • Sure, I get it, Jason. It's just in live, when you say "A or B", they usually don't think about possibility of "A and B", more likely "only A or only B". Thanks for such a detail answer :)
    – tiju
    Commented Nov 2, 2018 at 8:31

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