D-days are significant days that have a major impact on our lives. These days can signify the start or end of an important event or phase in our lives. Synonyms for D-days include landmark days, milestone days, defining moments, turning points, critical moments or key dates. Whether it's the first day of a new job, the day we graduate from college, or the day we get married, these important events shape who we are and what we become. Whatever synonym we use, D-days serve as a reminder of the important moments in our lives and how they have shaped our journey so far.