Dictionary.com
Thesaurus.com

Hubble classification

British  

noun

  1. a method of classifying galaxies depending on whether they are elliptical, spiral, barred spiral, or irregular

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of Hubble classification

C20: named after Edwin Powell Hubble