AbstractThe rise of complexity sciences has led to the development of new language about systems. Concepts such as ‘complex systems thinking'; or ‘complexity thinking'; have appeared in the literature, appealing to ways of thinking (in) complexity. The notion of ‘complex thinking,'; may be considered as referring to a mode of thinking more congruent with the complexity of the world. The widespread and sometimes undifferentiated usage of these concepts results in a lack of clarity and terminological confusion, which jeopardizes their heuristic and pragmatic value. We identify literature using terms related to thinking (in) complexity and use a combination of computational and qualitative methods to extract definitions and analyse their usage. We map the relationships of the concepts and their usage across different intellectual communities. Our goal is to clarify these concepts and to strengthen their pragmatic value for the promotion and management of positive changes in complex systems.