What does ‘drainage’ mean? What is a ‘drainage basin’?

What does ‘drainage’ mean? What is a ‘drainage basin’?
Ans. (i) The term ‘drainage’ means the river system of an area.
(ii) Some small streams flowing from different directions come together to form the main river, which ultimately drains into a large water body. The area drained by a single river system is called a ‘drainage basin’.