Sputum is the thick wet stuff that comes up from deep inside your lungs and throat when you cough hard. It is not ordinary spit from your mouth — spit is thin and watery and always there; sputum comes up from below, and usually only when you are ill.

Sputum痰 is the thick wet stuff that comes up from deep inside your lungs and throat when you cough hard是你用力咳嗽時，從肺部和喉嚨深處咳出來的濃稠濕黏物。It is not ordinary spit from your mouth它不是嘴巴裡普通的口水 — spit is thin and watery and always there口水是稀薄、水水的，而且一直都在； sputum comes up from below而sputum是從下面咳上來的， and usually only when you are ill而且通常只有生病時才會有。

This is a medical word. Doctors and nurses use it; ordinary people say phlegm, or just say "the stuff I cough up".

This is a medical word這是一個醫學用字。Doctors and nurses use it醫生和護理師會用這個字； ordinary people say phlegm一般人會說phlegm， or just say "the stuff I cough up"或者就說「我咳出來的東西」。

If you go to a hospital with a bad chest, they may ask you for "a sputum sample" — they want you to cough some into a small cup so they can test it and see what kind of infection you have.

If you go to a hospital with a bad chest如果你因為胸腔不舒服去醫院， they may ask you for "a sputum sample"他們可能會跟你要「a sputum sample（痰液檢體）」 — they want you to cough some into a small cup他們要你咳一些到一個小杯子裡， so they can test it and see what kind of infection you have這樣他們才能檢驗、看看你是哪一種感染。

Doctors care about its colour and thickness, because clear, yellow, green, or blood-streaked sputum each suggest something different.

Doctors care about its colour and thickness醫生會在意它的顏色和濃稠度， because clear, yellow, green, or blood-streaked sputum each suggest something different因為透明、黃色、綠色，或帶血絲的sputum，各自代表不同的狀況。

It has no plural in normal use; you say "some sputum", not "two sputums".

It has no plural in normal use它在一般用法裡沒有複數； you say "some sputum", not "two sputums"你會說"some sputum"，而不會說"two sputums"。