Wikipedia
Kammersänger
Kammersänger (male) or Kammersängerin (female), abbreviation: "Ks.", literally means "chamber singer." It is a German honorific title for distinguished singers of opera and classical music. Historically, the title was bestowed by princes or kings, when it was styled Hofkammersänger(in).
The title is given in Germany and in Austria usually on the recommendation of relevant national and local institutions. In the former German Democratic Republic, some concert halls bestowed this designation.
The equivalent designation in Sweden is Hovsångare (male) or Hovsångerska (female), in Denmark it is Kongelige Kammersangere.