Definitions:
a small, narrow river

a continuous flow of liquid, air, or gas

a continuous flow of data or instructions, typically one having a constant or predictable rate.

a group in which schoolchildren of the same age and ability are taught.

(of liquid, air, gas, etc.) run or flow in a continuous current in a specified direction

transmit or receive (data, especially video and audio material) over the internet as a steady, continuous flow.

put (schoolchildren) in groups of the same age and ability to be taught together.