1A sword or blade, especially a longer, double‑edged sword; the weapon itself (sword, blade).
古い城から一振りの剣が発見された。
A sword was discovered in the old castle.
舞台では本物の剣を使わず、模造品を用いることが多い。
On stage they often use a prop instead of a real sword.
彼は剣を携えて旅に出た。
He set out on a journey carrying a sword.
2A bayonet — a blade attached to a rifle for stabbing; the term can refer to such military blades.
訓練では銃と剣の扱いを学んだ。
In training they learned how to handle rifles and bayonets.
古い軍事博物館で多数の剣が展示されていた。
Many bayonets and blades were on display at the old military museum.
3Swordsmanship: the practice or art of fighting with a sword (e.g., kendo, fencing).
彼は若い頃から剣を学び、今は師範をしている。
He has studied swordsmanship since youth and is now an instructor.
剣の稽古は集中力と礼儀を重んじる。
Sword training emphasizes concentration and etiquette.
4In zoology, a term for a slender, pointed organ such as a stinger, ovipositor, or dart — a specialized usage.
ある昆虫のメスは長い剣を使って土中に卵を産み付ける。
The female of a certain insect uses a long ovipositor to lay eggs in the soil.