Highness

Highness (abbreviation HH) is a style (His Highness or Her Highness); plural Highnesses (abbreviation TH, Their Highnesses). It appears in front of the names of some members of various sovereign and non-sovereign families.

The style His/Her Highness ranks below His/Her Royal Highness, but above His/Her Serene Highness (although it traditionally ranked below Serene Highness in Romance countries).