Allnight is a word that signifies the entire night or an entire night's duration. It is often used to describe activities that take place overnight, such as parties, work shifts, or study sessions. However, allnight can be substituted with other synonyms to add more depth and clarity to the text. Alternative words to allnight include 'overnight', 'throughout the night', 'end-to-end', 'continuous', 'uninterrupted', 'around-the-clock', 'non-stop', 'twenty-four-hour', 'dark-to-dawn', and 'sleepless'. Using one of these synonyms can help capture the essence of an idea or description with more precision, and make the text more interesting to read.