How to Write 窦 (dòu) — Meaning “hole / sinus / cavity”

Imagine a cave (穴) that has a big 'SALE' sign (卖) at its entrance. This cave is so deep that it forms a sinus or cavity. You can remember that a '窦' is a hole where things are sold.

Write the top radical 穴 first with its roof cover (宀) and the two strokes below. Then write the bottom part 卖, making sure the vertical hook in 卖 is straight and not broken. A common mistake is to confuse the bottom with 买 (mǎi) or to make the 穴 too narrow.

All three share the 穴 radical, but they differ in the bottom part. 窑 has 缶 (a pottery jar) meaning a kiln, 窒 has 至 (arrive/block) meaning to block, and 窦 has 卖 (sell) meaning a hole. Visually, 窦's bottom looks like a cross and a 'buy' component combined.

窦 is most commonly used in medical terms like 鼻窦 (nasal sinus) and in the word 疑窦 (grounds for suspicion). It is also a Chinese surname, famously in the story '窦娥冤' (The Injustice to Dou E). You will not see it in daily conversation much, but it appears in formal and literary contexts.

Common words containing 窦 include: 疑窦 (yí dòu) — Grounds for suspicion; a suspicious point; 鼻窦 (bí dòu) — Nasal sinus; 窦道 (dòu dào) — sinus tract (medical).