noun
Medical and everyday term for mucus coughed up from the respiratory tract.
風邪をひいて、黄色いたんが出る。
I have a cold and I'm coughing up yellow phlegm.
医者にたんの検査をしてもらった。
I had the doctor examine my sputum.
The kanji 痰 is a phono-semantic compound: the radical 疒 (sickness) combined with 炎 (inflammation), suggesting a disease-related secretion. The reading たん is the on'yomi.