pus
Refers to the thick yellowish or greenish liquid produced in infected tissue. Common in medical and everyday contexts.
傷口から膿が出ている。
Pus is coming out of the wound.
膿を出すために切開した。
They made an incision to drain the pus.
corruption; rot; evils
Only with reading うみ
Figurative use, limited to the reading うみ. Describes moral decay, hidden evils, or deep-seated corruption in a system or society. Often used in fixed expressions like 膿を出す (to bring hidden problems to light).
We must root out all the corruption in the organization before reform can proceed.
bloody pus
Standard kanji for 'pus'. The reading うみ is the most common.
Kana spelling is common in everyday writing, especially when the kanji is considered difficult.
The kanji 膿 is a phono-semantic compound: the semantic component 肉 (flesh) and the phonetic component 農 (agriculture). The reading うみ is native Japanese, while のう is the on'yomi. The figurative sense likely developed from the idea of something festering and needing to be expelled.