细菌
xìjùn · HSK 6
bacteria
🦠 细 (fine/tiny) + 菌 (fungus) = tiny organisms, bacteria
The first character 细 means fine or slender, and 菌 means fungus or germ. Together they literally name the microscopic organisms we call bacteria — things too fine and small to see unaided.
细 — silk radical 糹 + 田 (field)
A semantic-phonetic compound. The silk radical 糹 supplies the meaning, since silk threads are fine and thin, giving 细 its sense of 'thin, fine, slender.' The right side 田 originally wrote 囟 (fontanel) as a phonetic hint, later simplified to 田 in modern script.