What is a galaxy with no definite shape or size called?
http://amazing-space.stsci.edu/resources/explorations/galaxies-galore/teacher/scientificbackground.html
A galaxy with no definite shape or size is called an "Irregular Galaxy." These galaxies do not have well-defined structure like spiral or elliptical galaxies. They often appear chaotic, with a mixture of stars, gas, and dust scattered throughout.
If you are curious about different types of galaxies or want to find more information about them, a good way to find answers is by searching online resources. You can use search engines like Google or visit reputable astronomy websites and databases such as NASA's website, the Hubble Space Telescope website, or the Sloan Digital Sky Survey website. These sources will provide detailed explanations, images, and information about different types of galaxies, including irregular galaxies.