Streamline/streamlined

In its modern sense, this technical term from hydrodynamics makes its appearance in the late 19th century where it was first used to describe how fluid, like a stream of water, flows around a line of least resistance, hence streamline. By the early 20th century, the same notion was applied to streams of air and so its usage passed from hydrodynamics into aerodynamics but retained its earlier connection with streams of water.