What does Karunanidhi's popular name 'Kalaignar' mean?

DMK chief M Karunanidhi, who passed away on Tuesday at the age of 94, was popularly known as 'Kalaignar', which means 'scholar of arts' and pronounced as 'Ka-lai-nyar'. Apart from being a political leader, Karunanidhi had worked as a screenwriter in Kollywood and wrote several poems and books like Ponnar Sankar, Thirukkural-Kalaignar Urai and Thenpandi Singam among others.