The phrase "hardest difficulty" refers to the most challenging or demanding level of something. It implies a high degree of difficulty, requiring great skill and effort to overcome. The term can be used in various contexts such as video games where it refers to the highest level of challenge for players, or in academic settings where it may refer to the toughest courses or exams. In essence, "hardest difficulty" signifies a test of one's abilities and limits, requiring great determination and perseverance to overcome.