What is the meaning of Streamline?

A line that is tangent to the velocity of flow of a fluid; equivalent to the path of a specific particle in that flow.

On a weather chart, a line that is tangent to the flow of the wind.

To design and construct the contours of a vehicle etc. so as to offer the least resistance to its flow through a fluid.

To simplify or organize a process in order to increase its efficiency.

To modernise.

Source: wiktionary.org