母鸡 (mǔ jī) literally means 'mother chicken' and refers specifically to an adult female chicken — what English calls a 'hen'. The first character 母 (mǔ) means 'mother' or 'female', signaling gender, while 鸡 (jī) means 'chicken' — the general term for the bird species. Unlike the neutral 鸡, which can refer to chickens of either sex, 母鸡 explicitly identifies the female, especially one that lays eggs or raises chicks.

This word is commonly used in everyday contexts involving farming, cooking, animal husbandry, or casual observation — for example, when describing farm animals, buying eggs at a market, or telling children about animal life cycles. It’s a concrete, unambiguous noun with no honorific or stylistic register; it’s neutral in tone and appropriate for all ages and settings. Note that it is not used metaphorically or idiomatically in standard modern Mandarin.