Which word is closest in meaning to "perpetual" in the context of motion?

The word "perpetual" refers to something that is continuous and unceasing, often implying a state of ongoingness without interruption. In the context of motion, it suggests that the motion occurs without any breaks or pauses. The term "continuous" captures this essence perfectly, indicating that the motion is sustained over time without any stops.

In contrast, "timed" suggests a specific schedule or frequency, which doesn't align with the idea of uninterrupted motion. "Mobile" refers to the capability to move or be moved but doesn't inherently imply the absence of interruption. "Inconstant" implies variability and changeability, which directly opposes the idea of being perpetual. Therefore, "continuous" is the word that most accurately conveys the meaning of "perpetual" when discussing motion.