Defense is a multifaceted and multi-category concept. The unilateral approaches of numerous theorists, especially the military ones, did not refer to its essence. There were numerous attempts to define it in all periods of the human society development. From the earliest simple human communities to this day, the defense have been treated in accordance with the will and level of knowledge of those who made decisions on the status, form and organization of a particular human community. It can be reliably asserted that the underlying causes of non-scientific, incomplete and, in most cases, incorrect approaches and definitions of the defense, both as a military category term and as a function, lie primarily in the development levels of defense sciences and, to some extent, its practices. In order to reach, from a scientific and professional point of view, a more complete, more expedient, and more acceptable understanding and definition of the concept of defense, it is necessary to start from its etymological meaning, conditionality, properties, and the most important functions. This is the path of creating a scientific basis for further consideration of the elements that will lead to an acceptable definition. Also, space will be created and new issues will be opened up, which will attune the considerations of defense from the general and military aspects as a physical, group, national and collective status/condition.