While not specifically a technical term, the word ellipsis refers to the “three periods” that are often used to indicate that something is continued or hidden. In its simplest terms, an ellipsis simply means “there is more”.
Quite literally, three periods in a row – such as “…” comprise an ellipsis.
Ellipses are used frequently when something to be displayed is too long for the space allocated. For example, an ellipsis typically appears at the end of a menu bar that has more items than can be displayed. Clicking on the ellipsis causes the rest to appear. Ellipses are also often used to indicate that something has been hidden (such as a signature or replied-to original in Gmail).
In more general writing, ellipses simply indicate that there is more, that text is continued, either explicitly at some other location, or conceptually, as in an unfinished expression of a thought.
See also: hamburger.