Definition of reason
(Entry 1 of 2)
1a
: a statement offered in explanation or justification
gave reasons that were quite satisfactory
b
: a rational ground or motive
a good reason to act soon
c
: the thing that makes some fact intelligible : cause
the reason for earthquakes the real reason why he wanted me to stay— Graham Greene
d
: a sufficient ground of explanation or of logical defense
especially
: something (such as a principle or law) that supports a conclusion or explains a fact
the reasons behind her client's action
2a(1)
: the power of comprehending, inferring, or thinking especially in orderly rational ways : intelligence
(2)
: proper exercise of the mind
(3)
: sanity
b
: the sum of the intellectual powers
3
archaic
: treatment that affords satisfaction
reason
verbDefinition of reason (Entry 2 of 2)
1
: to use the faculty of reason so as to arrive at conclusions
2a
: to talk with another so as to influence actions or opinions
can't reason with them
b
obsolete
: to take part in conversation, discussion, or argument
1
: to discover, formulate, or conclude by the use of reason
a carefully reasoned analysis
2
: to persuade or influence by the use of reason
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
The Exceptions Quiz III
-
- Which of these words does not mean "nonsense"?

Test your visual vocabulary with our 10-question challenge!
TAKE THE QUIZ
A daily challenge for crossword fanatics.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridged
Words at Play
Ask the Editors
Share reason
Time Traveler for reason
The first known use of reason was in the 13th century
See more words from the same century