해가 넘어가다.

The phrase '해가 넘어가다' (hae-ga neom-eo-ga-da) is a combination of several Korean elements: * **해 (hae):** This is the native Korean word for 'sun'. Its etymology can be traced back to Old Korean, where similar forms like 'ᄒᆡ〮 (hoy)' are found. It's a fundamental word in Korean, deeply rooted in the language's history and not borrowed from Chinese. * **-가 (-ga):** This is a subject particle in Korean. It attaches to nouns to indicate that they are the subject of the sentence. It doesn't have a deep independent etymology but serves a grammatical function that has been consistent throughout the development of the Korean language. * **넘어가다 (neom-eo-ga-da):** This is a compound verb formed from two parts: * **넘다 (neom-da):** This verb means 'to cross', 'to pass over', 'to go over', or 'to exceed'. Its etymology also goes back to Old Korean, appearing in forms like '넘〮다 (nèm-tá)'. It conveys the idea of moving from one side to another, or passing a certain point. In the context of the sun, it implies the sun moving from above the horizon to below it. * **-어 (-eo):** This is a connective ending used to link verbs, often indicating a sequence of actions or a state resulting from a previous action. In this case, it links '넘다' with '가다' to show the continuous action of passing over and then going. * **가다 (ga-da):** This is a very common verb meaning 'to go'. Its etymology is also ancient, found in Old Korean as '가〮다 (ká-tá)'. It signifies movement away from the speaker or a continuous progression. When combined with '넘다', it emphasizes the completion and progression of the action of crossing. Therefore, '해가 넘어가다' literally translates to something like 'the sun crosses over and goes' or 'the sun passes and proceeds'. This vivid imagery precisely captures the phenomenon of the sun descending below the horizon. The phrase has been in use in Korean for a very long time, likely as long as the component words have existed in their current or similar forms, reflecting a natural and descriptive way of expressing the sunset. It is a fundamental and widely understood expression in Korean, not a recent coinage.