关guān

關 (guān, "gate, to close") transforms dramatically between traditional and simplified forms—the traditional preserves the original pictograph of a city gate with crossbars, while the simplified reduces it to two simple strokes. As a component, it appears in characters like 送 (to send, literally "accompany through the gate") and 闖 (to rush in, "passing through"), preserving that sense of passage and barrier. The semantic thread connecting them all is the threshold: a place where things are let in, kept out, or overseen.