What is "meshterski"

Meshterski or Meshtrenski was the cant, or secret sociolect, of the south Bulgarian builders, bricklayers and masons. The name comes from the word мещра meshtra, "master", from Latin magister. Meshterski served a linguistically isolating purpose, enabling the builders to communicate in secrecy, and a socially isolating purpose, emphasizing the builders' perceived supremacy over their contractors.