According to § 14 of the German Civil Code (BGB), an entrepreneur is a natural or legal person or a legally capable partnership (in particular OHG, KG, partnerships and GbR) who, when concluding a legal transaction, acts in the exercise of his or her commercial or independent professional activity.
Freelancers, farmers, craftsmen and small traders not entered in the commercial register are also entrepreneurs, as are institutions under public law that provide services to citizens in return for payment, unless the provision of services is organised exclusively under public law (Palandt/Heinrichs, § 14 BGB marginal no. 2).
In the case of freelancers and so on, this only applies if the legal transaction was intended to serve entrepreneurial activity. Here it is primarily the purpose actually pursued that counts and not the impression created in the contracting partner's mind. An attribution contrary to the objectively pursued purpose can only be considered if the circumstances recognisable to the contracting partner clearly and unequivocally point to an entrepreneurial purpose. For example, it is not sufficient if a lawyer indicates her office as the delivery address when ordering lamps on the internet (BGH, judgement of 30 September 2009 - case no. VIII ZR 7/09).