(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"


(7)   Think logically
"The children must learn to reason"
(8)   Decide by reasoning; draw or come to a conclusion
"We reasoned that it was cheaper to rent than to buy a house"
(9)   Present reasons and arguments


  1. Action of the verb to reason.
  2. The deduction of inferences or interpretations from premises; abstract thought; ratiocination.