1. a person or thing that defines or establishes the meaning, nature, or boundaries of something
2. in computing, a tool or function that specifies or determines the definition of a variable, term, or concept
Usage: technical

Examples

• The dictionary is a key definer of standard English usage.
• Context is often the best definer of a word's true meaning.
• She acted as the definer of the project's scope and objectives.
• The compiler uses a definer to establish variable types.
• Cultural values serve as definers of social behavior.
• The contract acts as a definer of each party's responsibilities.