1. to become preserved as a fossil through natural processes over long periods of time
Usage: British spelling
2. to cause something to become preserved as a fossil
Usage: British spelling
3. to become rigid, outdated, or unable to change
Usage: British spelling; figurative

Examples

• The ancient tree slowly fossilises in the sedimentary rock.
• Heat and pressure fossilise organic matter over millions of years.
• Scientists study how different materials fossilise under various conditions.
• The dinosaur bone fossilises perfectly in the limestone.
• Without reform, the old system fossilises and becomes ineffective.
• Traditional practices can fossilise if they resist modern influences.
• The organization fossilises when it stops adapting to change.