General terms:
* Simultaneity: This is the most direct and formal term, emphasizing the state of happening at the same time.
* Concurrency: This term is more commonly used in technical contexts, especially in computing, to describe events happening at the same time.
* Coincidence: This emphasizes that the events happening at the same time are unplanned or unexpected.
* Simultaneousness: This is another formal term, less common than "simultaneity" but carrying the same meaning.
More specific terms:
* Overlap: This emphasizes that the events partially coincide in time.
* Co-occurrence: This implies that the events are statistically likely to happen together.
* Synchronicity: This term is used in a more philosophical context to describe meaningful coincidences.
* Intersection: This term is used in a more mathematical or logical context to describe the point where two events happen together.
The best word to use will depend on the specific context and the meaning you want to convey.