1. a stronghold or fortified area; a defensive structure
Usage: military/architectural
2. a person, place, or thing that strongly defends or supports particular principles, values, or ways of life
Usage: figurative

Examples

• The ancient castle served as a bastion against enemy attacks.
• The old fort’s bastions provided excellent defensive positions.
• The university remains a bastion of academic freedom.
• She was considered a bastion of traditional values in the community.
• The library has long been a bastion of learning and culture.
• The organization serves as a bastion for civil rights.
• This neighborhood is the last bastion of affordable housing in the city.