A lenticular galaxy is a type of galaxy. These galaxies have an elliptical shape and ill-defined spiral arms. Basically, they are a combinations of spiral and elliptical galaxies. Examples include the Cartwheel Galaxy and NGC 4479. They are disk galaxies that have lost most of its interstellar matter, therefore have very little ongoing star formation. Because of this, they contain a lot of aging stars like elliptical galaxies.