What is an Estuarine environment

I need to know for an assignment, it would be great in simplest form, but i ALSO need a scientific definition !!

thanks so much !

An estuary is a river mouth that has been flooded by rising sea levels and is thus much wider than would be expected from the size of the river. Estuaries are tidal, often exceptionally so. The river brings a deposits silt on the sea bed of the estuary which are exposed at low tide. These mudflats provide habitats for invertebrates and the wader birds that feed on them. The water in estuaries is salty, but often less so than the open sea. Estuaries are common on coastlines because sea levels have been rising since the end of the last ice age. The Thames and the Severn are examples of UK rivers with estuaries. Chesapeake Bay is the largest in the US

An estuary is a bay that is isolated from the ocean somehow and doesn't have rivers flowing into it. The water has a low level of dissolved oxygen in it and is usually associated with swamps. The water is full of carbon rich mud and chemically conducive to the chemical process or reduction (as opposed to oxidation). The carbon rich muds build up over time and can be buried and after a long time become peat and later coal.