Can an odachi be called a katana?


I was arguing with a friend about the meaning of the word "katana". There are
very large swords (some of them longer than 200cm) known as
[odachi](https://en.wikipedia.org/wiki/%C5%8Cdachi). My friend claimed that
calling them a katana is not wrong since they are also swords and katana is
just a general way to refer to swords. I checked from Wikipedia and words of
some sword types include "katana" kanji (刀) in them. For example:

Katana:刀  
Tachi:太刀  
Odachi:大太刀

Does that mean he is right and they can be called as a katana, or is "katana"
used for describing specific types of swords only?




刀 ("katana") **as a Japanese word** refers to (usually thin) single-edged
swords in general, not swords in general. Etymologically, "kata" means
"single". Double-edged swords are not called 刀, but most Western sabers and
Persian shamshirs are safely called 刀 by Japanese speakers (although more
specific names like サーベル and シャムシール are also common). [This
section](https://ja.wikipedia.org/wiki/%E5%88%80#%E4%B8%BB%E3%81%AA%E5%88%80%E3%81%AE%E7%A8%AE%E9%A1%9E)
in Japanese Wikipedia lists the types of 刀 in the world. That said, when
people say 刀 without any context, it primarily refers to Japanese ones used by
Japanese samurai. When you need to specifically refer to Japanese 刀, you can
use 日本刀 (nihontō).

Note that _katana_ **as an English word** normally refers to Japanese swords
only, and you probably have to respect this fact while you're speaking in
English. Not all loaned words retain the original meaning. (A similar example
is flute/フルート. In English, _flute_ is a general term that includes
[_shakuhachi_](https://en.wikipedia.org/wiki/Shakuhachi), but フルート in Japanese
refers only to western concert flutes. If I said _shakuhachi_ is a type of
フルート to a Japanese speaker, they might think I'm crazy.)

As for 大太刀 (odachi), from a Japanese speaker's point of view, it's certainly a
subtype of 刀. If it doesn't match your image of classic _katana_ (-as-
English), I would say that's a problem in English, not Japanese.

**EDIT:** As is explained in sundowner's answer, Japanese people sometimes
distinguish "打刀 (uchi-gatana) = (日本)刀 in the narrow sense" and "太刀 (tachi)",
although the difference is not large. [This Wikipedia
article](https://en.wikipedia.org/wiki/Tachi) is based on the narrow sense of
katana. So it's something like this:

[![enter image description
here](https://i.stack.imgur.com/iOcmP.png)](https://i.stack.imgur.com/iOcmP.png)

So, you and your friend were both correct but were discussing based on the
different definitions of the word. Which is correct depends on how strict you
are categorizing Japanese weapons.




刀 ("katana") **as a Japanese word** refers to (usually thin) single-edged
swords in general, not swords in general. Etymologically, "kata" means
"single". Double-edged swords are not called 刀, but most Western sabers and
Persian shamshirs are safely called 刀 by Japanese speakers (although more
specific names like サーベル and シャムシール are also common). [This
section](https://ja.wikipedia.org/wiki/%E5%88%80#%E4%B8%BB%E3%81%AA%E5%88%80%E3%81%AE%E7%A8%AE%E9%A1%9E)
in Japanese Wikipedia lists the types of 刀 in the world. That said, when
people say 刀 without any context, it primarily refers to Japanese ones used by
Japanese samurai. When you need to specifically refer to Japanese 刀, you can
use 日本刀 (nihontō).

Note that _katana_ **as an English word** normally refers to Japanese swords
only, and you probably have to respect this fact while you're speaking in
English. Not all loaned words retain the original meaning. (A similar example
is flute/フルート. In English, _flute_ is a general term that includes
[_shakuhachi_](https://en.wikipedia.org/wiki/Shakuhachi), but フルート in Japanese
refers only to western concert flutes. If I said _shakuhachi_ is a type of
フルート to a Japanese speaker, they might think I'm crazy.)

As for 大太刀 (odachi), from a Japanese speaker's point of view, it's certainly a
subtype of 刀. If it doesn't match your image of classic _katana_ (-as-
English), I would say that's a problem in English, not Japanese.

**EDIT:** As is explained in sundowner's answer, Japanese people sometimes
distinguish "打刀 (uchi-gatana) = (日本)刀 in the narrow sense" and "太刀 (tachi)",
although the difference is not large. [This Wikipedia
article](https://en.wikipedia.org/wiki/Tachi) is based on the narrow sense of
katana. So it's something like this:

[![enter image description
here](https://i.stack.imgur.com/iOcmP.png)](https://i.stack.imgur.com/iOcmP.png)

So, you and your friend were both correct but were discussing based on the
different definitions of the word. Which is correct depends on how strict you
are categorizing Japanese weapons.

