Nouns

(n)shoala sandbank in a stretch of water that is visible at low tide
(n)shoal, shallowa stretch of shallow water
(n)school, shoala large group of fish“a school of small glittering fish swam by”

Verbs

(v)shallow, shoalmake shallow“The silt shallowed the canal”
(v)shallow, shoalbecome shallow“the lake shallowed over time”