: what are the differences, if any, between all the words for "sword" in Japanese? Are bokken and bokuto synonymous? Are ken, katana, iaito, shinken, tachi, etc. etc. all the same, or are there some subtle differences that separate them?
Bok ken and and boku, as Tim notes, both use the the same character for the "boku" & and "bo" portions. "Ken" originally meant "straight sword" and isn't used commonly by itself anymore. When it is used by itself, the character for "ken" is usually read as "tsurugi." When combined with other characters in words it is read "ken" as is in kendo and shinken.
A shinken is literally a "true sword," in other words a real, genuine, sharp as a razor, sword.
An iaito is a practice sword, generally made of aluminium-zinc alloy. These were invented after World War 2 so that new iai students would have affordable practice equipment. The new rules about who could make steel blades limited production to only 2 blades a month per licensed swordsmith. And it requires 5 years as an apprentice to earn a license.
Tachi are swords mounted to be hung at your side, edge down, and the saya was well secured to the wearer so it would stay in place during riding and fighting.
A katana is a sword mounted to be worn edge up, with the saya (sheath) simply thrust through the belt. This is really a peace time mounting for use in day to day life, where you would remove the katana any time you entered a home.
Wakizashi are short swords, generally less the 2 feet in length.
Kodachi means "little tachi" and these are similar to wakizashi.
"Daito" means "big sword" and can refer to either tachi or katana.
"Shoto" means "little sword" and can mean just about anything shorter than a tachi or katana.
Tanto just means "short sword" and refers to daggers under about 1' (30 cm).
That's more than you wanted to know.
Peter "the Budo Bum" Boylan