Shoal

Shoal: One meaning of shoal shares its etymology with shallow and refers to a shallow place in a deeper body of water. A shoal might be formed by a sandbar.

An independent meaning of shoal is a crowd or large group. The etymology of school of fish comes from shoal and is separate from school of students which share its etymology with scholar.

His wife and daughters, however, made much of me, and introduced me to their friends, who came in shoals to call upon me.

A Book for Today: Erewhon by Samuel Butler