A nail-biter is a term used to describe a situation that is very suspenseful and thrilling. It is often used to describe a movie, book, or game that keeps the audience or players on the edge of their seats. The crossword solutions for the term nail-biter are 'thriller, ' which is an apt description for a nail-biter. A thriller is a genre of entertainment that is designed to keep the audience engaged and excited with unexpected plot twists and intense action.