Lisan-ul-Ghalib was the designation of:

Hafiz a celebrated Persian poet was honored with the title Lisan-ul-Ghalib meaning “The Tongue of the Unseen.” The word “designation” is a noun meaning a formal title or label given to someone. Alternatives could be “title” “epithet” or “appellation.” This honor recognized his unmatched eloquence and mastery of Persian lyric poetry. Titles like this show how poets were celebrated in their societies for their ability to express deep truths beautifully.