mainstay
n. countablen. the most important part of something that keeps it strong or successful. You use this to describe a person or thing that others depend on.
n. a person or thing that acts as the chief support or central component of a system or activity. Originally referring to a rope that supports a ship's mast, it now primarily describes essential economic or social pillars.
Tourism is the mainstay of the local economy.
For decades, the small family-owned bakery has been a mainstay of the neighborhood, providing fresh bread to generations of residents.
While the tech sector is growing rapidly, traditional manufacturing remains the mainstay of the national GDP, providing the stable employment necessary for long-term economic health.
From Middle English main stai, equivalent to main + stay (“rope”).
Often used in the singular with the definite article ('the mainstay of') or as a predicate nominative.