1. a person who tests something to check its quality, safety, or performance
2. a device or instrument used for testing something
3. a small sample of a product given free to potential customers

Examples

• The software tester found several bugs before the program was released.
• She works as a food tester for a major restaurant chain.
• The mechanic used a battery tester to check the car’s electrical system.
• The store offered a free tester of the new perfume.
• I tried the lipstick tester before buying the full size.
• The antique bed had an ornate wooden tester above it.