the cause of an event or situation or something that provides an excuse or explanation
The reason for the disaster was engine failure, not human error.
The reason why grass is green was a mystery to the little boy.
The detective sought to uncover the reason behind the mysterious disappearance.
It's essential to understand the reason for a problem before attempting to solve it.
The scientist explained the reason for the unexpected outcome of the experiment.
Beyond the apparent actions, there is often a deeper reason driving human behavior.