reason

noun:a cause, explanation, or justification for an action or event
- The reason for the delay was a technical malfunction.
noun:the power of the mind to think, understand, and form judgments logically
- Human beings are distinguished by their capacity for reason.
verb:to think, understand, and form judgments logically
- We must reason our way through this complex problem.
noun:a motive or purpose behind someone’s behavior
- She had a clear reason for quitting her job.
noun:a logical basis or argument that supports a claim
- He gave a compelling reason to adopt the new policy.
noun:sound judgment or common sense
- Use your reason when deciding whether to invest.
verb:to persuade someone by appealing to logic or rational argument
- He tried to reason with his brother about the dangers of speeding.