Definition of "Plate"

[…] ; but the tributary waters of the Plate issuing from the eastern and western plateaus, flow towards each other, unite in the heart of the continent, and continue over the central plain to the Atlantic.

1832, The Edinburgh Encyclopædia conducted by David Brewster, volume 17, page 288

To the southwest 235 miles of Uruguay's coast meet the muddy waters of the Plate. The tide plays tricks with the sediment-laden discharge of the great river and drives it back onto the coast, […]

1947, Betty de Sherbinin, The River Plate republics, page 221

A series of lucky shots from the small fort at Colonia had set fire to the Lord Clive, which was unable to manoeuvre in the shallow waters of the Plate. It did not stop burning till the flames reached the water line.

2002, Andrew Graham-Yooll, Imperial Skirmishes: War and Gunboat Diplomacy in Latin America, page 6

It would be preferable in view of the shortage of ammunition to blow her up in the shallow waters of the Plate and to have the crew interned.

2004, Dudley Pope, The Battle Of The River Plate: The Hunt For The German Pocket Battleship Graf Spree, page 184: translating a telegram sent in 1939 to the German Foreign Office