highness comes from Old English hēanes ('height, exaltation'), from hēah ('high') + the noun-forming suffix -ness; the royal title sense ('Your Highness') developed in Middle English. Morphologically, the ending is part of the etymology: the suffix is attached to the older base named in the history, producing a later English derivative. In present English, the noun sense is "the state of being high; a title of honour for royalty", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as high, higher, and highest. Its semantic neighborhood includes loftiness, eminence, elevation, and majesty, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Old English hēah and Proto-Germanic *hauhaz.