The term 'boundary zone' is composed of two words: 'FRONT' (5 letters) and 'AREA' (4 letters). The word 'FRONT' refers to the leading edge or boundary of something, while 'AREA' refers to a particular geographical region. Together, the two words form the phrase 'boundary zone', which can be defined as an AREA that marks the boundary between two different regions or territories. This boundary zone can be physical, such as a mountain range or river, or it can be political, such as a border between two countries.