Sutherland, JoshuaBeale, DeanDazzi, FrancescoSinger, JanetSmith, GaryOosthuizen, RudolphLanza, AlfonsoCureton, KenMcKinney, Dorothy2026-01-302026-01-302026-01Sutherland, J., Beale, D., Dazzi, F. et al. 2026, 'Managing variations in meaning: guidance for using complexity and related terms', Systems Engineering, vol. 29, no. 1, art. e70007, pp. 114-125, doi : 10.1002/sys.70007.1098-1241 (print)1520-6858 (online)10.1002/sys.70007http://hdl.handle.net/2263/107742Correction added on 18-December-2025, after first online publication: The authors Dean Beale and Francesco Dazzi are added as the corresponding authors in this version.The term “Complexity” is widely used across disciplines, where it often represents distinct but related concepts such as complicatedness, emergence, difficulty, uncertainty, and chaos. This variability in usage can create miscommunication and misunderstanding, even within structured organizations like the International Council on Systems Engineering (INCOSE). This paper addresses this challenge by offering guidance tailored to three primary audiences—General/Casual, Practitioner, and Research—on using and interpreting “Complexity” effectively across trans-disciplinary contexts. Unlike efforts that prescribe a single definition, the approach here respects the variety of interpretations while providing techniques and ontologies to clarify usage. To illustrate, the paper compares different “Complexity” definitions, fostering awareness of both the similarities and distinctions. By promoting a common understanding, rather than a definition, this paper lays essential groundwork for future initiatives aimed at developing a unified scientific basis for “Complexity”, enabling clearer, more consistent communication, and application.en© 2025 The Author(s). Systems Engineering published by Wiley Periodicals LLC. This is an open access article under the terms of the Creative Commons Attribution License.ComplexityDefinitionsArticle