Happening or operating at the same time.
Example:
The convicted killer was sentenced to serve three concurrent life terms in prison.
Things that are concurrent usually not only happen at the same time but also are similar to each other. So, for example, multitasking computers are capable of performing concurrent tasks. When we take more than one medication at a time, we run the risks involved with the concurrent drug use. And most movie theaters today run several movies concurrently.