1. having existed for a long time and being widely accepted or recognized
2. successful and respected in a particular field or profession
3. officially created or founded

Examples

• The company is an established leader in the technology industry.
• She’s an established author with several bestselling novels.
• The established rules must be followed by all employees.
• Harvard is one of the most established universities in America.
• The restaurant has been established in this location since 1952.
• He challenged the established way of doing things.
• The established church played an important role in medieval society.