1. the quality or state of occurring at the same time

Examples

• The simultaneity of the two events made it difficult to determine which caused the other.
• Einstein’s theory of relativity challenged our understanding of simultaneity in space and time.
• The simultaneity of the fireworks display created a spectacular show.
• Scientists studied the simultaneity of brain activity in different regions during learning.
• The simultaneity of multiple crises overwhelmed the emergency response team.
• The concert featured the simultaneity of various musical instruments playing together.