Lost in NAMs-lation: A review of animal-free science definitions

The use of terminology related to animal-free science has grown rapidly over the past two decades; however, definitions and interpretations of key terms remain inconsistent across global regulatory, scientific, and policy contexts. The term 'new approach methodology(ies)' (NAM(s)) exemplifies this issue: Though rarely used prior to 2020, its uptake in scientific literature has increased substantially in recent years. Despite this growth, the term, and its acronym, 'NAM', is used with varied meanings, leading to misunderstanding regarding the types of methods described. Similarly, the term 'animal' is defined differently across common language, scientific discourse, and legal frameworks, resulting in further ambiguity in what constitutes 'animal-free science'. These variations can hinder productive dialogue and collaboration, particularly in international settings. This manuscript maps the current landscape of definitions of key terms such as 'NAM', 'animal', and 'animal-free', drawing on regulatory, academic, and institutional sources to enhance understanding of the range of existing interpretations. By improving transparency and clarity in terminology, this effort seeks to support more coherent and effective global communication in the field of animal-free science. In addition, the definition of NAM, as agreed by the members of the International Collaboration on Cosmetics Safety, is put forward as a recommendation for future alignment on the term. Tabulated definitions and sources are provided as a reference tool.