To vacillate is to keep changing your mind, and to keep changing it back. It is not the same as changing your mind once because you found out something new — that is just being sensible. Vacillate means you go one way, then the other way, then the first way again, and you do not settle.

To vacillate is toVacillate的意思就是 keep changing your mind一直改變主意， and to keep changing it back然後又改回去。 It is not the same as它跟 changing your mind once改變一次主意不一樣 because you found out something new如果是因為發現了新的事情才改— that is just being sensible那只是明智而已。 Vacillate means你go one way先往一邊走， then the other way再往另一邊走， then the first way again然後又走回第一邊， and you do not settle一直定不下來。

People use it about decisions (she vacillated between the two job offers for weeks), about opinions (the government vacillated on the new rule), and sometimes about feelings (he vacillated between hope and worry).

People use it大家用這個字 about decisions講決定 (she vacillated between the two job offers for weeks)（她在兩個工作邀約之間猶豫了好幾個禮拜）， about opinions講意見 (the government vacillated on the new rule)（政府在新規定上搖擺不定）， and sometimes about feelings有時候也講感受 (he vacillated between hope and worry)（他在希望和擔心之間搖擺）。

It is a formal word. You will meet it in books, news articles, and business writing far more than in talk between friends. In everyday speech people say "can't make up my mind", "keeps going back and forth", or "keeps flip-flopping". If you said "stop vacillating!" to a friend, it would sound like a joke, or like you were being a bit grand on purpose.

It is a formal word它是個正式的字。 You will meet it你會在 in books, news articles, and business writing書、新聞文章、商業文件裡遇到它 far more than in talk between friends遠比在朋友聊天裡多。 In everyday speech平常講話 people say大家會說 "can't make up my mind"「can't make up my mind（拿不定主意）」， "keeps going back and forth"「keeps going back and forth（一直搖來搖去）」， or "keeps flip-flopping"或「keeps flip-flopping（一直反覆）」。 If you said如果你對朋友說 "stop vacillating!" to a friend「stop vacillating（別再猶豫了）！」， it would sound like a joke聽起來會像在開玩笑， or like you were being a bit grand on purpose或是故意講得很誇張正式。

It carries a small judgement. When someone says a person vacillates, they usually think that person is weak, or slow, or afraid to choose. It is rarely a compliment.

It carries a small judgement它帶著一點批評的味道。 When someone says a person vacillates當有人說一個人vacillate， they usually think that person is weak他們通常覺得那個人很軟弱， or slow或很慢， or afraid to choose或不敢做決定。 It is rarely a compliment這很少會是稱讚。

The pattern is usually "vacillate between A and B", or "vacillate over/about something".

The pattern is usually常見的用法是 "vacillate between A and B"「vacillate between A and B」， or "vacillate over/about something"或「vacillate over/about something」。

Though actually — the original picture in the word is a physical one, something swaying or wobbling, not able to stand still. That older "wobble" meaning is basically gone from modern English; if you use it, people will hear only the mind-changing sense.

Though actually不過其實—— the original picture in the word這個字原本的畫面 is a physical one是很具體的， something swaying or wobbling是某個東西在搖晃、晃動， not able to stand still站不穩。 That older "wobble" meaning那個比較舊的「搖晃」意思 is basically gone from modern English在現代英文裡基本上已經消失了； if you use it如果你這樣用， people will hear only the mind-changing sense大家只會聽成「改變主意」這個意思。