shoal

Short definition from Wiktionary

Adjective

1. 1
   Shallow.

Noun

1. 1
   A sandbank or sandbar creating a shallow.
2. 2
   A shallow in a body of water.
3. 3
   Any large number of persons or things.
4. 4
   A large number of fish (or other sea creatures) of the same species swimming together.

Verb

1. 1
   To arrive at a shallow (or less deep) area.
2. 2
   To cause a shallowing; to come to a more shallow part of.
3. 3
   To become shallow.
4. 4
   To collect in a shoal; to throng.