Katana or tachi means sword in Japanese
剣 けん "ken" is also another word for sword and is just as common.
"katana" tends to refer to a single-edged sword, especially a Japanese sword.
"tachi" is a long sword.
"ken" is fairly generic "sword", although it was previously commonly used to refer to a double-edged sword.
it is a zonpoto
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The actual translation of "sword" is 剣 (ken).
I think the original answerer is trying to say zanbattou (斬馬刀), which is a specific type of especially large Japanese sword.
