The phrase "kept step" implies a harmonious movement or synchronized action. Its antonyms, therefore, suggest discord or lack of coordination. Some of the antonyms for "kept step" include disorganized, chaotic, uncoordinated, erratic, haphazard, and unsynchronized. In these situations, instead of acting in a coordinated and synchronized way, people, or things, are moving in different or conflicting directions. For example, in a dance performance or a military drill, people are expected to keep step with each other to create a cohesive experience. However, when they fail to do so, the performance loses its rhythm, resulting in a less enjoyable experience.