The oracle-bone scribes drew exactly what a butcher or woodcarver held: a single curved blade with a straight spine and one small stroke marking the handle. Later the picture straightened into two brush-strokes — a long diagonal for the blade's back, a hooked stroke for its cutting edge — but the same silhouette of a blade with a handle is still there in today's 刀. Compressed onto the side of a character, it becomes the 刂 radical, standing guard over hundreds of words about cutting.
A piece of culture
The blade of the crescent moon The most famous 刀 in Chinese legend belongs to General Guan Yu, later worshipped as a god of loyalty and war: the 青龙偃月刀 (Qīnglóng Yǎnyuèdāo), the "Green Dragon Crescent-Moon Blade." Its name combines 月 (moon), for the blade's curved shape, with 刀 — both characters you now own. The weapon is a star of the Ming-dynasty novel Romance of the Three Kingdoms and of Chinese opera and temple statues ever since, even though historians doubt the real Guan Yu, who lived in the 2nd–3rd century, ever wielded a polearm of this design — it belongs more to legend than to the battlefield.
Use it in a real word
大刀
dàdāo · daai6 dou1
saber; broadsword — literally "big blade"; you already know 大