A chain of stages where each hands its output to the next. A pipeline's speed is its slowest stage.
From pipe (Vulgar Latin pipare, to chirp, of imitative origin, later a tube) and line (Latin linea, a linen thread); a 19th-century oil-industry compound for a chain of stages that hands each output to the next, only as fast as its slowest length.
A chain of stages where each one hands its result to the next — and whose whole speed is set by whichever stage in it is slowest.