Lighting-up time refers to the time of day when artificial lighting is required due to darkness outside. Some synonyms for lighting-up time include twilight, nightfall, dusk, and evening time. These terms are commonly used to describe the gradual fading of sunlight and the emergence of a darkening sky. Other synonyms include sundown, crepuscule, and gloaming, which are more poetic and less commonly used in everyday language. Regardless of the chosen synonym, lighting-up time represents a turning point in the day when the natural light is no longer enough, and it is time to illuminate indoor spaces and continue with regular activities.