(American) the action of closely keeping to something/someone and mimicking its/their actions, often without much thought or consideration, in a way that yields identical results rather than variation;
e.g. They followed the directions in lockstep, and attained perfect results.
(noun)
(American) a method of marching as a group in which all members are in step and each follows the person in front of them as closely as possible;
e.g. They moved in lockstep, appearing to form a single large body.