The fourth generation of district heating is an established expression for new features and configurations. This generation’s overarching goal is to develop heating concepts for smart energy systems contributing to the net-zero carbon emission society by substituting older district heating generations, originally developed for fossil fuels. The evolving technology generation has to consider the future challenges of lower heat demands, increased cooling demands, and integration of renewable and recycled thermal sources. Driven by these challenges, the district heating and cooling community is fast growing and very dynamic in its innovation. This trend can be observed in the development of cold networks for both heating and cooling. Several new systems in Europe, North America, and Asia have applied newly developed heating and cooling network configurations. It is essential to consolidate these novel technical solutions into the entire family of fourth generation at this stage of development to efficiently and effectively deploy and expand district heating and cooling solutions. This paper exemplary discusses ambiguous terms to demonstrate the shortfall of not having a broad and internationally accepted vocabulary. The conclusion gives suggestions for harmonising expressions, terms, and definitions introduced and used during the last years. An interactive vocabulary will facilitate innovation and a common language. ©2021 The Author(s). Published by Elsevier Ltd