In the 21st century, we observe a dynamic development of technology, which has a significant impact on the military field. One of the most innovative developments in this field is autonomous systems. They have the ability to independently perform specific tasks or activities, minimizing or completely eliminating the need for human participation. They represent a breakthrough in the way warfare is conducted and have the potential to change the face of armed conflicts. This work focuses on defining concepts related to autonomous weapon systems and analyzing their potential use in the context of armed conflicts in the 21st century. The paper raises issues related to the degree of autonomy and definition problems in the area of autonomous weapon systems. Attention was paid to the classification of this type of systems, because there are many categories that are different from each other. The relationship between robotics and autonomous weapon systems has also been described. The aim of the article is to define the scope of definitions in the area of autonomous weapon systems. The main research problem of the work was defined in the form of a question: How does defining concepts in the field of autonomous weapon systems affect their military use? The main hypothesis was adopted in the work, which assumes that defining autonomous weapon systems is necessary to use them during armed conflicts. The article uses domestic and foreign literature. The work uses the institutional and legal method. The article focuses on the definition of autonomous weapon systems and their potential use during armed conflicts in the 21st century. The benefits, risks and challenges associated with these systems are presented, as well as legal and ethical issues that should be considered. Understanding these aspects is crucial for further research and discussion on the role of autonomous weapon systems in the modern military world.