What is a group of Galaxies called?

A group of galaxies is commonly called a Host. Other collective nouns you may see include Nursery and Belt.

Collective nouns are words used to describe groups of things, and in the case of galaxies, the term utilized is "cluster". A cluster refers to a grouping of galaxies in the vast expanse of the universe. These clusters are structures observable through telescopes and they consist of numerous galaxies held together by gravitational forces. Clusters offer a captivating sight, as they showcase the brilliant diversity and immense scale of our cosmos. Typically, they consist of tens to thousands of individual galaxies that vary in size, shape, and brightness. Sometimes, especially in larger clusters, one can spot elliptical, spiral, and irregular galaxies all together. The giant bright galaxies, often at the center of the cluster, can appear captivating against a backdrop of smaller counterparts. Such clusters generally form when galaxies draw closer to each other due to gravitational attraction. As they gather over time, they create evolving structures with the galaxies moving, merging, or even colliding. Galactic interactions trigger star formation, turbulence, and create cosmic turbulence within these exceptional communities. They offer a glimpse into the intricate web of interaction and evolution occurring within the universe. Galactic clusters allow astronomers to study various aspects of the cosmos. By exploring these communities, scientists gather insights about the distribution of galaxies, estimate the mass of the universe, examine dark matter's impact, understand galaxy formation and evolution, and gain valuable information regarding the expansion of the universe. In summary, collective nouns used to describe groups of galaxies are "clusters." These mesmerizing assemblages of galaxies not only captivate the imagination but also facilitate a deeper comprehension of the vastness and wonders of the universe.