As said to end conversations (especially on the phone): mmm-bye.

When and how did this form/usage start?

  • 2
    Urban Dictionary includes entries for "m-bye" in the relevant sense from April 15, 2008, and May 10, 2010. The latter entry claims that the expression is "Common colloquialism in rural western United States." As with anything else in Urban Dictionary, the claims about origin are not objectively reliable—since they rest on bald assertion—but at least these entries establish that "m-bye" has been in use for more than a dozen years. I suspect that "m-bye" was influenced by "m-kay" and "m-hmm" (from "uh-huh").
    – Sven Yargs
    Commented Jul 31, 2020 at 3:57
  • 2
    An Elephind newspaper database search turns up this possibly relevant instance from the "Where the Heart Is..." personals section of the Valentine's Day edition of the [Kent, Ohio] Daily Kent Stater (February 14, 1986): "Sweetheart, It's almost over, we've just begun. Bubbly is on me. love you, M-Bye. P.S. I would have enclosed roses but I already sealed the envelope!!! "
    – Sven Yargs
    Commented Jul 31, 2020 at 4:10

2 Answers 2


"Hmm" and "mmm" are, in this case, interchangeable; they both serve as fillers.

There is no proven theory of the etymology of "hmm" or "mmm," but there are some speculative ones.

Regarding the symbolism of "hmm," Anatoly Liberman said:

The first h-sound is simply a substitute for breath, and the second m-sound, since the mouth is closed, is symbolic of the fact that we're not quite sure what to say [Live Science]

It can be reasonably inferred that the same can be applied to "mmm," except for the part about the "h-sound."

In the same Live Science article, Nicholas Christenfeld speculates that "hmm" is popular because of its neutrality. Again, the same could be inferred about "mmm."

The Lexico dictionary defines "hmm" as an interjection used to express reflection or hesitation.

"Mmm bye" was most likely said because "bye" is too abrupt, so "mmm" can act as a filler—for just the right amount of time—which makes "bye" softer/more gentle. It is easy to say because the "m" sound can directly transition into the "b" sound in "bye," (because your lips are closed) which is what makes "mmm bye" smoother than "bye."

Also, saying "mmm" before "bye" gives you a moment to think about whether you want to add anything else to the conversation before hanging up. This is more aligned with its definition than the above use, but I believe that both are just as valid.


MMM is in anticipation of "B".

I find descriptions of the use of "mmm-bye" going back several years and all across the country but most often in the South or warm weather states. The best explanation of it's use and meaning is to say good-bye and close a conversation. It is often used in the general collection of closing phrases such as, "OK, well, we'll talk later, take care, mmm-bye." As stated there is as yet no etymological history of this term.

The use of this extends as far North as North Dakota and has little to do with region. However, in the warm weather (generally Southern) states speech often becomes slower and more relaxed, along with much activity. [This explanation was given to me by several good Southerners.] Clearly the purpose of the mmm is to continue, in anticipation, the use of the B in Bye.

The /b/ being a bilabial stop or plosive consonant requires the lips to be closed to begin with. Rather than anticipate by saying "B-B-B-Bye" the laid back, relaxed method is to start the voice before the lips get into action. These leaves us with the calm "mmm" for as long as comfortable to be finished off with the plosive B, then Y and E, mmmmmmBye. A comfortable and relaxed conclusion.


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