What term refers to a short, continuous sloping line of low ground that usually cuts into the side of a ridge?

The term that accurately refers to a short, continuous sloping line of low ground that usually interrupts the side of a ridge is "draw." A draw is typically characterized by a depression or a channel cut into the terrain which can guide water runoff and can serve as a travel corridor or tactical point in military operations.

The other terms have distinct meanings: "swale" usually refers to a shallow, low-lying area that can hold water but is distinct from the more defined structure of a draw; "valley" describes a larger area of land that is lower than the surrounding terrain, often with more significant dimensions; "gulley" describes a steeper, more pronounced channel that has been carved out by the action of water, which can be deeper and more defined than a draw. Each term relates to landforms, but "draw" is the specific term that encapsulates the characteristics described in the question.