The quality or state of being concurrent; the fact of happening, existing, or acting at the same time.
From concurrent (Latin concurrens, running together) + -ness (English nominalizing suffix). This formation allows abstract discussion of the philosophical or temporal concept of simultaneous occurrence.
Physics and philosophy use concurrentness to describe when events lack a clear cause-and-effect relationship because they're happening truly simultaneously—it's the noun that captures the weirdness of things that occur 'at exactly the same moment' without one causing the other.
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