걱정이 되다.

The phrase '걱정이 되다' is composed of '걱정' (geokjeong), meaning 'worry' or 'anxiety', and '이 되다' (i doeda), meaning 'to become' or 'to turn into'. **Origin of 걱정 (geokjeong):** The word '걱정' itself is a native Korean word, not a Sino-Korean compound, although its precise ancient etymology is somewhat debated among linguists. It is generally believed to have originated from an older form of Korean. One common theory traces '걱정' back to the Middle Korean word '걱정ᄒᆞ다' (geokjeong-hoda), which meant 'to be troubled' or 'to be anxious'. The nominal form '걱정' then emerged from this verb. The 'ᄒᆞ다' (hoda) ending is a common verbal suffix in Middle Korean. Some etymologists suggest a connection to '걱다' (geokda), meaning 'to be difficult' or 'to be troubled', or perhaps even onomatopoeic origins related to the sound or feeling of distress, although these are less commonly accepted. **Origin of 되다 (doeda):** '되다' is a fundamental and ancient Korean verb with a wide range of meanings, including 'to become', 'to be made', 'to turn out', 'to be possible', and 'to be accomplished'. Its origin can be traced back to Old Korean. It has maintained its core meaning of transformation or realization over centuries. **Combination '걱정이 되다':** When '걱정' (worry/anxiety) combines with '이 되다' (to become), it literally translates to 'worry becomes' or 'it becomes worry'. This idiomatic expression perfectly captures the process of anxiety or uneasiness setting in or developing within a person. The structure 'Noun + 이/가 되다' is a very common grammatical pattern in Korean to express that something turns into a state or an entity. In this case, '걱정' (anxiety) is the subject of the verb '되다' (to become), implying that the state of anxiety is arising or affecting the speaker. Over time, '걱정이 되다' has become the standard and most natural way to express the feeling of becoming anxious or uneasy about something in Korean, reflecting the dynamic nature of emotions as they arise and take hold.