The term 'OLD NORSE LETTER' can be summarized as the word 'RUNE', which is a four-letter word. Runes were an ancient alphabet used by Germanic and Scandinavian peoples during the Middle Ages. They were used for writing, divination, and magical purposes. Runes were inscribed on stones, wood, metal, and other materials. The Old Norse language was written using runes until the Latin alphabet was adopted in the 12th century.