In English language a lot of complex words and forms exist which are not so commonly known by native English speakers as well. Only learners of English whose keen mission is to understand the grammatical aspects of language are aware of such things.
One such element of English grammar is elliptical sentence or ellipses.
When a word or a group of words is omitted from a sentence without changing the context of the sentence, it is termed as ellipses. When an ellipses occurs, it is understood that the word or words are missing and still the meaning of the sentence is clear.
A sentence is said to be elliptical when an ellipses occurs in it.
Jess has four dogs; Allison, three.
In the above sentence the word has has been omitted from the second part of the sentence but the meaning of the sentence is till clear.