The word "night-line" refers to various things, depending on the context. It could mean a late-night television show, a nighttime border demarcation, or even a group of people waiting overnight in a line for a popular event or product release. However, there are many other synonyms one could use depending on the actual context. Some synonyms for "night-line" include "night shift," "graveyard shift," "nocturnal hours," "dark hours," "midnight hours," "after-hours," "late-night," "evening hours," "nightly," and "overnight." These synonyms not only help to make your writing more unique and varied but also provide the reader with a better understanding of the context in which the term is used.