morphology

The English word, morphology, refers to the form and structure of something, and in astrophysics, the word is often used for extended sources, perhaps most often for galaxies. The word is used in descriptions and in classification terms that are specifically not based upon function or dynamics, but rather the shape and appearance of the object. The Hubble classification of galaxies is termed a morphological classification. The term also can be used for protoplanetary disks, planetary nebulae, supernova remnants and other clouds, as well as stellar clusters, galaxy clusters, and planets and asteroids.