<p><strong>Noun</strong></p><ul><li>Nautical: the stay that secures the mainmast forward</li><li>a person or thing that acts as a chief support or part: Coffee is the mainstay of the country's economy</li></ul><p><strong>Synonyms</strong></p><ul><li>prop</li><li>anchor</li><li>bulwark</li><li>pillar</li></ul>