The European Commission’s (EC) Joint Research Center (JRC) published on February 13, 2019, a report entitled An overview of concepts and terms used in the European Commission’s definition of nanomaterial. The report supports the implementation of the EC’s Recommendation on a definition of nanomaterial (2011/696/EU). It addresses the definition’s key concepts and terms and discusses them in a regulatory context. Corresponding to the broad scope of the definition, the report states that its considerations can be applied across all relevant legislative areas; they are not specific to any particular piece of legislation. The report provides recommendations for a harmonized and coherent implementation of the nanomaterial definition in any specific regulatory context at the European Union (EU) and national level.