Do you mean sentence fragment? The question is not quite clear. If that's what you mean a sentence fragment is an incomplete sentence. Example: Running down the hill.
"You're just a figment of my imagination!" "Yes there are answers here it is just a figment of your imagination that there are not."
This sentence is a figment of your imagination.
The noises I heard coming from the attic were a figment of my imagination.
The invisible friend of the four year old girl is a figment of the girl's imagination.