舊

舊 is a compound ideograph, originally composed of:

臼 (“mortar, base”) and 丨 + 日 (“sun, time”), symbolizing something that has endured or worn through the passage of time.

The character conveys the sense of things ground down by time → “old, worn, former.”

In early scripts, 舊 often appeared with variant forms, sometimes closer to 臼 combined with 日. Over time, it stabilized into the current form.

In Korean, 구 (舊) appears in many compounds relating to the past, old things, or what is previous:

구식 (舊式) – old style, outdated

구교 (舊敎) – the old religion (Catholicism in contrast with Protestantism; or Buddhism vs. newer sects, depending on context)

구정 (舊正) – lunar new year (lit. “old new year”)

구원 (舊怨) – old grudge, long-standing resentment

신구 (新舊) – new and old