The contemporary labour legislation, as a rule, provides the definition of the term "employer". While the reason for defining the concept of "an employee" rests on the need to determine the personal field of application of labour legislation, the essence of providing a legal definition of the term "employer" is to identify the entity that is responsible for fulfilling the obligations towards employees and other temporarilly engaged individuals, as well as their unions and other representation insitutions. Despite the importance of providing an accurate definition, comparative labour legislation can barely offer a classification of the term "employer" which indicates that the legislation bodies have managed to overcome the circular (idem per idem) definition. Additionally, the present definitions are not adjusted to triangular (and multilateral) labour-generated relations. Consequently, in order to harmonize the legal framework with the changes which occur in economic reality, an increasing number of labour law systems initiate the process of introducing a new legal model of plural-employer. In that context, the author of this paper first considers the need to re-conceptualize the term "employer" and analyzes the current unitary and (new) plural-employer conceptions of this term. Finally, using the example of digital platforms, the author demonstrates the inadequacy of the existing legal definitions of the concept "employer" and emphasizes the need for adopting new ones which are more adjusted to the labour market realities.