reason

noun

1
the capacity for rational thought or inference or discrimination
we are told that man is endowed with reason and capable of distinguishing good from evil
2
a fact that logically justifies some premise or conclusion
there is reason to believe he is lying
3
an explanation of the cause of some phenomenon
the reason a steady state was never reached was that the back pressure built up too slowly
4
a justification for something existing or happening
he had no cause to complain
they had good reason to rejoice
5
a rational motive for a belief or action
the reason that war was declared
the grounds for their declaration
6
the state of having good sense and sound judgment
his rationality may have been impaired
he had to rely less on reason than on rousing their emotions

1
think logically
The children must learn to reason
2
decide by reasoning; draw or come to a conclusion
We reasoned that it was cheaper to rent than to buy a house
3
present reasons and arguments

Also useful for “reason”:Unscrambler— Rearrange the letters in “reason”