Definition
Means a natural or legal person engaged in an economic activity, irrespective of its legal form, including partnerships or associations regularly engaged in an economic activity
Source
Point (18) of Article 4 of Regulation (EU) 2016/679 of the European Parliament and of the Council of 27 April 2016
Link
https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32016R0679
