What does reason mean?
Reason has several closely related meanings. As a noun, it can refer to the cause or explanation for something, such as the reason a road was closed or the reason a person chose a particular course of action. It can also mean a justification or consideration: if someone has reason to worry, the available facts provide a basis for concern. In a more intellectual sense, reason denotes logical thought and the ability to form sound judgments, as in the Enlightenment belief that reason could guide human affairs. As a verb, reason means to think logically or to give an explanation or justification. The word is used broadly in both formal and informal English, but “reason” as a verb often sounds more deliberate and analytical than ordinary verbs such as “think.” Its close relatives include “rational,” “rationale,” and “ration,” all reflecting the historical idea of calculation, proportion, and reasoned judgment.
A cause, explanation, or justification for an action, event, belief, or decision; also, the faculty or process of logical thought.
"There is no reason to doubt the accuracy of the report."
In the sense of logical faculty, “reason” is often used collectively or philosophically, as in “the power of reason.”
To think about something logically, or to explain or justify something by giving its causes or grounds.
"The researchers reasoned that the treatment would be most effective in younger patients."
The verb is commonly used in formal, analytical, or argumentative contexts.
The plural is used for separate causes, explanations, justifications, or grounds.
"The company gave several reasons for delaying the launch."
The word “reason” shares its root with “ratio”: both come from the Latin idea of calculating and comparing.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does reason come from?
The word comes through Middle English from Old French raison, ultimately from Latin rationem, a word associated with calculation, reasoning, and proportion. Its Latin relatives include ratio (“proportion”) and ration (“reason,” “calculation”), from which English developed “rational,” “rationale,” and “ration.” The original sense developed from the idea of counting or calculating, and the modern meanings reflect both calculation in the sense of careful thought and the explanation or grounds provided by such thought.
Related word forms
How reason is actually used
The noun is extremely common in neutral formal and informal contexts. The verb “reason” is somewhat more formal when used to mean “think logically,” while its use meaning “explain or justify” is especially common in formal and argumentative writing.
Easily confused with reason
A reason can be a general cause or explanation, whereas a rationale usually refers specifically to the reasoning or justification behind a decision, plan, or policy.
A cause is what produces an effect, while a reason may be an explanation, justification, or basis for action and need not be the direct cause.