The "Great Disappointment" refers to the event on October 22, 1844, when followers of the American religious leader William Miller anticipated the Second Coming of Jesus Christ. Miller's predictions, based on his interpretation of the Bible, led many to believe that the world would end on that date. When the day passed without incident, it caused widespread disillusionment among his followers. This event marked a significant moment in the history of American religion, leading to the formation of new religious movements, including the Seventh-day Adventist Church. The Great Disappointment highlighted the challenges of prophetic interpretation and the impact of failed expectations on religious communities.