reason - noun

a rational motive for a belief or action

an explanation of the cause of some phenomenon

the capacity for rational thought or inference or discrimination

the state of having good sense and sound judgment

a justification for something existing or happening

a fact that logically justifies some premise or conclusion

reason - verb

• decide by reasoning; draw or come to a conclusion
• present reasons and arguments
• think logically

reason - thesaurus

argue   cause   conclude   ground   grounds   intellect   rationality   reasonableness   understanding