irregular galaxy

noun

, Astronomy.

1. a galaxy with no specific form and a relatively low mass.

irregular galaxy

1. A galaxy that does not have the clearly defined shape and structure of typical elliptical, lenticular, or spiral galaxies. Irregular galaxies typically contain large amounts of gas and dust, and their stars are often young. They account for only a small percentage of known galaxies. Some irregular galaxies are the result of gravitational interactions or collisions between formerly regular galaxies. Many irregular galaxies orbit larger regular ones; the Magellanic Cloud galaxies orbiting the Milky Way are examples.
2. Compare elliptical galaxySee more at Hubble classification system

Word History and Origins

Origin of irregular galaxy¹

First recorded in 1960–65

Example Sentences

In early observations, the burst appeared to have originated near an unidentifiable, amorphous blob, which astronomers initially thought was either a single, irregular galaxy or a group of three distant galaxies.

From Science Daily

But NGC 6822 is an example of an irregular galaxy.

From BBC

But the light signature revealed that the object was indeed located in a small, irregular galaxy about 500 million light-years from Earth.

From Scientific American

At the edge of the small, irregular galaxy that he was studying in the constellation Centaurus, he saw a large burst of light brighter than the entire galaxy itself that had not been there before.

From Time Magazine Archive