～とは
what is X / regarding X
～とは combines the quotation particle と with the topic particle は. Placed after a word or phrase, it presents that word itself as the thing being questioned or defined, like opening a dictionary entry or an essay with “What is X?” or “X means ...”.
It feels more formal and weighty than plain は, and it is common in titles, lectures, and written explanations.
1. Asking what something is
With a question word, ～とは asks for the essence or definition of the topic, not just casual information about it.
自由とは何か。
“What is freedom?”
- 自由（じゆう）= freedom
- とは = topic marker for definitions (as for what X is)
- 何（なに）= what
- か = question marker
2. Giving a definition
The same ～とは introduces the answer: the sentence that follows explains what the word means, often ending in ～のことだ (“refers to ...”).
親友とは、何でも話せる友達のことだ。
“A best friend is a friend you can talk to about anything.”
- 親友（しんゆう）= best friend
- とは = topic marker for definitions
- 何でも（なんでも）= anything
- 話せる（はなせる）= can talk (about)
- 友達（ともだち）= friend
- のことだ = refers to, means
In casual conversation, the same job is usually done by ～って or ～というのは. ～とは is the crisp, formal version.
How to form it
Noun (or quoted phrase) + とは
- 自由（じゆう）= freedom → 自由とは = what freedom is / freedom means ...
- 幸せ（しあわせ）= happiness → 幸せとは = what happiness is
- 友情（ゆうじょう）= friendship → 友情とは = what friendship is
Key idea
～とは puts a word itself on the table and asks or states what it fundamentally is. It's the Japanese equivalent of starting a dictionary entry with “X: ...” or an essay with “What is X?”.
Other N3 grammar
Updated .