松鼠 (sōng shǔ) literally means 'pine rat'—a compound noun formed from 松 (sōng), meaning 'pine tree', and 鼠 (shǔ), meaning 'rat' or 'mouse'. Historically, the name reflects the animal’s habit of living in pine forests and storing pine nuts. In modern usage, it refers broadly to tree-dwelling squirrels found across China, especially the common Eurasian red squirrel (Sciurus vulgaris) and native species like the Pallas’s squirrel.

The word is neutral in register and commonly appears in children’s books, nature documentaries, biology classes, and casual conversation about wildlife. Unlike some animal names that require classifiers, 松鼠 typically pairs with the general classifier 只 (zhī) when counting—e.g., 一只松鼠 (yì zhī sōng shǔ). It does not carry metaphorical or idiomatic meanings in standard usage, making it straightforward for learners to grasp and apply.