とは — What Do You Mean By / The Sheer Fact That
とは has two related uses. First, it introduces a term or topic to be defined or explained, functioning like 'the definition of X' or 'X means…'. Second, and more emotionally, it expresses strong surprise, admiration, or shock at an unexpected fact — 'to think that…!' or 'I can't believe…!'. The surprised usage often trails off, leaving the emotion implied.
Structure
[Noun / Plain clause] + とは
Examples
常識とは、人によって違うものだ。
Joushiki to wa, hito ni yotte chigau mono da.
What we call 'common sense' varies from person to person.
とは marks 常識 as the term being defined and explained.
こんな所で君に会うとは、驚いたよ。
Konna tokoro de kimi ni au to wa, odoroita yo.
To think I'd run into you in a place like this — what a surprise!
とは after the plain verb 会う expresses shock at the unexpected event.
彼が犯人だったとは、信じられない。
Kare ga hannin datta to wa, shinjirarenai.
I can't believe that he was the culprit!
Past plain clause + とは conveys disbelief at a revealed fact.
• The surprise usage carries strong emotion; often the final predicate (驚いた, 信じられない) is even dropped. • The definition usage is common in explanatory and academic writing. • Do not confuse with the quotative と + topic は in casual speech.
Commonly confused with
The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones とは is tested against.
vs というのは
というのは also defines/explains a term but is softer and more conversational; とは is more compact and can additionally carry the 'surprise' nuance, which というのは cannot.
vs なんて
なんて expresses surprise or disdain more casually and colloquially; とは feels a touch more literary and can also serve the neutral definitional role.
More emphasis
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