After dark refers to the night time when the sun has set and the sky has turned dark. There are several synonyms that can be used to describe this time of day. Some commonly used synonyms include the phrase "in the night time," which refers to the period of time when the stars are visible in the sky. Another synonym is "at night," which is used to describe activities or events that take place during the evening hours. "After hours" is another synonym that refers to activities or events that take place after normal business hours. Finally, "twilight" is a synonym that refers to the period of time right before the sun sets and the sky turns completely dark.