Post meridians, also known as PM, refers to the hours of the day that come after noon and before midnight. There are several synonyms for post meridians, including afternoon, evening, and night-time. The afternoon refers to the period of time that starts after noon and before the evening, from around 12:00 pm until 5:00 pm. The evening usually refers to the time between 5:00 pm and 9:00 pm, and the night-time starts after that. These terms are often used to describe different periods during the day for different purposes, such as scheduling appointments, working hours, or making plans with friends and family.