Afterlight is a term commonly used to describe the soft glow that remains in the sky after sunset or after a source of light has disappeared. While not many words serve as true antonyms for afterlight, a few words may come to mind. The opposite of afterlight could be pre-dawn or predawn, as this refers to the time period just before sunrise. Another word that could be considered an antonym for afterlight is darkness or twilight, as these terms signify the absence of residual light from a previous source. Overall, while not many true antonyms exist for afterlight, there are a few terms that convey a sense of opposing concepts.