What does the collective noun of galaxy mean?

There isn't a widely accepted collective noun specifically for a group of galaxies. However, here are some options you could use:

Formal:

* A cluster of galaxies: This is the most common and accurate term, as galaxies often group together in clusters.

* A supercluster of galaxies: For larger groupings of galaxy clusters.

Informal:

* A swarm of galaxies: This conveys a sense of movement and vastness.

* A constellation of galaxies: This emphasizes the patterns and connections between galaxies.

Ultimately, the best collective noun depends on the specific context and the desired tone.