Irregular Galaxy
A galaxy that lacks a distinct regular shape, unlike spiral or elliptical galaxies. Irregular galaxies often result from gravitational interactions or collisions, leading to chaotic appearances without a defined structure. They typically contain abundant gas and dust, facilitating active star formation.
Source: science.nasa.gov
APODs including "Irregular Galaxy"
M82: An Irregular Galaxy
28/07/1995
July 28, 1995 M82: An Irregular Galaxy Credit: The Electronic Universe Project Explanation: Not all galaxies have spiral structure like our Milky Way. Many have smooth elliptical shapes, but also many have irregular shapes such as the bright sky object M82, the 82nd object on Messier's list. The strange structure of this galaxy is thought to be caused by young stars ejecting gas in energetic bubbles, and by lanes of absorbing dust. For more information on M82 see The Electronic Universe Project's write-up. Many images of Messier objects can be found in The Electronic Universe Project's The Galaxy Gallery: Messier Objects.