Dater (noun)

1. A person who is dating someone or going on dates with different people.
2. A machine or tool that is used to stamp a date on an object.

Origin:

Early 18th century: from date (verb), on the pattern of traitor.

Examples:

1. He was a notorious dater, always going on dates with different women.
2. She was a serial dater, always looking for the next best thing.
3. The dater is used to stamp the date of production on the product.
4. The dater is a machine which stamps the date of expiration on food products.
5. The dater is a tool that is used to mark the date on documents.