The phrase "remarkable milestone" refers to a significant achievement or accomplishment that is worthy of being noticed and celebrated. It represents an important point in time, often marking progress or success in a particular endeavor. The word "milestone" implies a landmark or turning point, while the adjective "remarkable" emphasizes its exceptional nature - something outstanding or noteworthy that stands out from ordinary achievements. When used together, this phrase conveys a sense of great significance and importance in reaching such an accomplishment.