‘Gēbo’ (胳膊) is the standard Mandarin word for 'arm' — specifically the entire upper limb from shoulder to wrist, though in everyday speech it often refers to the upper arm or the arm as a whole. The two characters are inseparable in modern usage: 胳 (gē) and 膊 (bo) each carry no independent meaning in this context and only combine to form this disyllabic noun. Historically, they derive from ancient terms related to limbs and joints, but today 胳膊 functions as a single lexical unit.

This word is neutral in register and used widely across spoken and written Chinese — in medical contexts (e.g., checking arm strength), daily descriptions (e.g., stretching one’s arms), and idiomatic expressions (e.g., 胳膊肘往外拐 — 'elbow pointing outward', meaning disloyal). Unlike the more formal or technical term 手臂 (shǒubì), 胳膊 feels natural and colloquial, especially in northern dialects and informal conversation.