A 'nighter' is a term used to describe a person who stays up all night, usually to work on a project or complete a task. The crossword solutions for the term 'nighter' are ALL, STAY, and LATE. All can be used to describe someone who stays up all night, as they are 'all night'. Staying up LATE is another way to describe someone who is a nighter, as they are staying up LATE into the night. Finally, 'LATE' is another way to describe someone who is a nighter, as they are staying up LATE into the night.