Main entry word is a term that describes the primary word or phrase used to introduce the subject of a text. Synonyms for main entry word include key term, headline, header, title, and primary subject. These synonyms are useful in various contexts, such as in library cataloging, database indexing, and search engine optimization. The use of a main entry word or its synonyms can make it easier for readers to locate and identify relevant information, and it can also help to streamline the organization of a document or database. Choosing the right synonym for main entry word depends on the specific needs and goals of the user and the context in which it is used.