The word elliptical is derived from the oval shape known as an ellipse. Many comets have an elliptical orbit around the Sun that brings them closer at some times and farther away at others.
The adjective elliptical refers to the shape of an ellipse, which is an elongated circle, stretched into an oval. This word can also be used to describe a way of speaking that cuts out extra, unnecessary language. When writers use an elliptical style, it sometimes makes the work obscure and hard to interpret.