Concurrent (adjective)

1. Happening or existing at the same time.
2. Operating or performed at the same time.

Origin:

Mid 16th century: from latin concurrent- "meeting together", from the verb concurrere (see concur).

Examples:

1. Concurrent events are events that happen at the same time.
2. Concurrent processes are processes that are performed at the same time.
3. Concurrent users are users that are accessing a system at the same time.
4. Concurrent sessions are sessions that are being held at the same time.
5. Concurrent operations are operations that are being performed at the same time.