kru'uze fu'ivla

x1 moves/behaves in a manner such that it is only (or primarily) due only to external forces, having trajectory/evolution-path x2; x1 cruises.

This notion is weaker than that of free-fall. It is not exactly the same notion as the "cruise" in "cruise control", which is a rudimentary partial autopilot system which maintains speed of vehicles relative to the ground (maintaining velocity in the presence of friction, drag, etc. requires acceleration, which is produced internally in most "cruising" vehicles in practice); "cruise control" is "motion/behavior maintenance" (specifically, "speed maintenance via some internal means"). When thruster are off, this is what spacecraft do in outerspace.