estuary

noun

1. The wide part of a river where it flows into the sea, where fresh water mixes with salt water.

   B2

   countable

   • "The city lies on an estuary where the river meets the sea."B1
   • "Estuaries are important habitats for many species of fish and birds."B2
   • "The ecological health of the estuary has declined due to industrial pollution."C1