切断 literally means 'to cut' (切) and 'to break/sever' (断) — together, it expresses the action of completely separating or stopping something by cutting, either physically or metaphorically. It emphasizes a decisive, often irreversible interruption: a wire, a connection, blood flow, communication, or even a relationship. Unlike simpler verbs like 剪 (jiǎn, 'to cut with scissors'), 切断 implies forceful, complete separation — often with tools (knives, lasers) or in technical/medical contexts.

This word is commonly used in medical settings (e.g., cutting off blood supply during surgery), engineering (disconnecting power lines), digital security (cutting off network access), and figurative speech (e.g., cutting off contact). It’s transitive and usually requires an object (e.g., 切断电源, 切断联系). While it can describe physical cutting, its modern usage leans heavily toward abstract interruptions — especially where safety, control, or urgency is involved.