I noticed that many in web development talk of "callout" and "callout menu" but they all seem to talk of different things.
According to Wiktionary one meaning is:
An annotation that pertains to a specific location in a body of text or a graphic, and that is visually linked to that location by a mark or a matching pair of marks.
This seems to fit an example of code named "callout"
However I don't see the added value of the word. I'd just say "alert" if it's a mere communication, or "dialog"/"menu" if there is something to do with it. If the point is in the coming out of some other part of the interface, I'd just use the metaphor of the speech bubble.
Is "callout" yet another variant of the "popup" scheme like "flyover", "popover", "popout" and many others? Sometimes I have the impression that many words are created just as euphemisms to avoid the derogatory term "popup".