What does the word delta mean in science not math?

1.            delta in science means river. it is the delta river which is located in region of egypt. it is a nearly flat plain that diverge its branches on the mouth of the river. delta river is a landform located at the mouth of the river. it is very healthy landform because it is abundant from water that flows throughout its body. usually, delta forms from the deposition of sediment. as time pass, it will start develop into a landform in a triangular shape.