Data set for the paper "From national to supranational institutionalisation: A microdiachronic study of the post-accession evolution of the Polish Eurolect" (under review).The objective of this paper is to investigate the evolution of the Polish Eurolect, a supranational translator-mediated variety of legal Polish by: (1) analysing circumstances in which it emerged and took shape; and (2) tracking its development from the formative pre-accession to mature post-accession stage. The first part documents challenges faced at various...