unstable
unstable — 形容詞
1. not firmly fixed, positioned, or balanced, so that something or someone is likel
不穩定的
物體或結構不牢固，容易移動或倒塌
not firmly fixed, positioned, or balanced, so that something or someone is likely to move, fall, or break.
The old wooden chair wobbled because one of its legs was unstable.
那張舊木椅搖搖晃晃，因為其中一條腿不穩固。
collocation: unstable + leg / structure / surface
Niran placed the vase on an unstable shelf, and it crashed to the floor.
Niran 把花瓶放在一個不穩固的架子上，結果花瓶掉到地上摔碎了。
After the earthquake, engineers declared the bridge unstable and closed it.
地震過後，工程師宣布那座橋不穩定，並將其關閉。
Liang held the ladder for Beatriz because the ground beneath it was uneven and unstable.
Liang 幫 Beatriz 扶穩梯子，因為腳下的地面凹凸不平，很不穩固。
A pile of loose stones made the path unstable for hikers carrying heavy bags.
一堆鬆散的石頭讓這條步道對背著沉重背包的登山者來說很不穩固。
- unsteady
less formal, often used for movement or gait rather than fixed position
- wobbly
informal; describes something that moves from side to side when touched
- precarious
more formal; suggests danger of collapsing or falling at any moment
- rickety
informal; describes old, poorly made structures likely to break
用法筆記
Frequently used for physical objects (furniture, buildings, ground surfaces) and extended to abstract things such as political systems or economic conditions.
常見錯誤
2. describes a person whose emotions, behaviour, or state of mind changes suddenly
情緒不穩的
人的情緒或精神狀態急遽變化
describes a person whose emotions, behaviour, or state of mind changes suddenly and extremely, often because of a mental health condition.
After losing her job, Noa became emotionally unstable and struggled to sleep.
Noa 失業後情緒變得很不穩定，連睡覺都有困難。
collocation: emotionally / mentally unstable
The court ordered a psychological evaluation to determine whether the defendant was mentally unstable.
法院要求進行心理評估，以判斷被告是否有精神不穩定的情況。
Selim's friends noticed he had become increasingly unstable and urged him to see a therapist.
Selim 的朋友發現他越來越情緒不穩，勸他去看心理治療師。
Maeve worried that her brother's unstable behaviour might get him into trouble at school.
Maeve 擔心弟弟不穩定的行為可能會讓他在學校惹上麻煩。
The report described the patient as psychologically unstable and in need of long-term care.
報告描述該病患心理狀態不穩定，需要長期照護。
- volatile
suggests sudden, explosive mood swings; slightly more formal
- unbalanced
less clinical; suggests a lack of mental equilibrium
- erratic
focuses on unpredictable behaviour rather than internal state
- stable
the opposite in mental/emotional contexts
- well-adjusted
positive informal term for healthy mental state
用法筆記
Often used in clinical, legal, or journalistic contexts. Avoid using this term casually or as an insult in everyday speech because it carries a strong negative judgement about a person's mental health.
常見錯誤
3. describes a chemical substance or compound that readily changes its composition,
易反應分解的
化學物質容易反應或分解
describes a chemical substance or compound that readily changes its composition, decomposes, or reacts with other substances, often in a dangerous or unpredictable way.
The lab assistant stored the unstable compound in a special container to prevent an explosion.
實驗室助理將那個不穩定的化合物存放在特殊容器中，以防止爆炸。
collocation: unstable + compound / chemical / substance
Jin warned the trainees that the mixture becomes unstable if heated too quickly.
Jin 警告實習生，如果加熱太快，混合物就會變得不穩定。
Some radioactive elements are naturally unstable and break down into other elements over time.
某些放射性元素天生不穩定，會隨著時間分解成其他元素。
Élise checked the safety data sheet before handling the unstable reagent in the laboratory.
Élise 在實驗室處理不穩定的試劑前，先查閱了安全資料表。
- reactive
emphasises a tendency to react with other substances
- volatile
specifically suggests rapid evaporation or dangerous reaction at room temperature
- decomposable
technical; focuses on breaking down into simpler components
用法筆記
Mostly used in scientific or technical writing. In everyday language, sense 1 or 2 is preferred. The term does NOT describe emotional states when used in a chemistry context.