The crossword solution for the term 'KING'S MIDDLE NAME' is 'LUTHER', which is a six-letter word. This is in reference to Martin Luther King Jr., an American civil rights leader who was active in the mid-20th century. He is best known for his role in the advancement of civil rights using nonviolent civil disobedience based on his Christian beliefs. His middle name, Luther, was given to him in honor of German theologian Martin Luther, who was a major figure in the Protestant Reformation.