shoal

noun

1. a large group; mass; crowd
2. a large school of fish

intransitive verb

noun

1. a shallow place in a river, sea, etc.; a shallow
2. a sandbar or piece of rising ground forming a shallow place that is a danger to navigation, esp. one visible at low water

intransitive verb

transitive verb

1. to make shallow
2. to sail into a shallow or shallower part of (water)