An ellipsis (with an i) is a punctuation mark consisting of 3 dots used either to indicate that words or phrases are omitted in a sentence (usually a quote) or, in common usage, to pause in thought or allow a thought to trail off without completing it. Examples:
Thoreau notes: “I learned . . . that if one advances confidently in the direction of his dreams, . . . he will meet with . . . success. . . .” [thepunctuationguide.com/ellipses.html]
Well . . . what do you think?
I thought we were in agreement, but . . . ?
Most word processing programs have an automatic replacement feature that inserts unspaced dots and calls it an ellipsis. You can change the settings, however, to make it correctly spaced.
When you wish to end a quote with the ellipsis, you must add the period as the fourth dot, spacing before it. Example: President Kennedy said, “Ask not what you can do for your country . . . .”
The plural word “ellipses” (with an e) refers to the dots themselves, not the combined punctuation mark.