tester
nounUK /ˈtestə/
US /ˈtestər/
A person or thing that checks if something works well.
The tester tried the new toy to make sure it was safe.
OTHER MEANINGS
2. A small sample of a product given to people to try.
The shop gave out free testers of the new shampoo.
3. A person who takes a test or exam.
The testers waited quietly for their exam papers.
4. A device or machine used to check something.
He used a battery tester to see if the batteries were full.
5. A canopy over a bed, like in old castles.
The old bed had a fancy tester above it.