During the Middle and Late Neolithic, especially in south-eastern Sweden, the archaeological material sometimes reveals a type of hybrid ceramic that was previously classified as a Battle-axe ceramic. But as recent as the latter part of the 1990s, this hybrid pottery was again noticed by researchers in a compilation of Neolithic pottery. In this compilation, the name Third Group is used as a collective name for the hybrid ceramics. Further studies have since resulted in a relatively restrictive template with several subgroups where the material has been defined as the Third Group. This work is a type of definition analysis with an element of comparative analysis where the use of the term Third Group is analyzed, as well as the definition behind the term. The main goal of the study is that during the relatively short period the term has been in use, be able to follow and gain a deeper understanding of how words and definitions in technical language are used, developed, and discussed. The aim of the study is to show that communication and language use within one's own profession is extremely relevant for further research.