We have a pack of dogs, a flock of birds, a forest of trees – the word used for groups of angels is “choir.”
Here is a clever little diagram to describe and explain the choirs of angels in all their different categories. (Click on the image for a larger image).
According to many theologians, like St. Thomas Aquinas, there are 9 choirs of angels in 3 hierarchies.
Visit https://churchpop.com for more things like this.
To learn more about Angels, I have a new talk (actually an interview) entitled “Angels: the Good, the Bad and the Unexplained.” You can see or purchase a copy here.