Whereby (adverb)

1. By means of which; through which.
2. By reason of which; as a result of which.

Origin:

Middle english: from where + by.

Examples:

1. The new technology, whereby waste is turned into energy, is being tested.
2. He came up with a new method, whereby the process was made more efficient.
3. The system was redesigned whereby the error rate was reduced.
4. The company adopted a new policy, whereby all employees are required to attend a training.
5. He found a solution, whereby the problem was solved in a cost-effective way.