- 1
To undo the buttons on clothing — a shirt, a coat, a , a cuff, a pocket — so that it opens. Plain and physical, like . You can unbutton the whole garment (he unbuttoned his shirt) or just part of it (she unbuttoned the top button, he unbuttoned his collar). Both are normal. Notice that this verb is fussier than it looks: the really has to be a button. A zip is unzipped, a buckle is , a knot is . English names the mechanism. Two small extras worth knowing. The past participle works as an adjective and is very common in descriptions of people: he stood there with his collar unbuttoned. And there is a figurative use for people — to unbutton, or to be unbuttoned, means to relax and stop being stiff and formal. Unbuttoned in that sense describes a loose, easy, unguarded mood: an unbuttoned interview, an unbuttoned laugh. It is not very frequent, and it belongs to writing more than to speech, but you will meet it, and it comes straight from the picture of a man his collar after work.
解開鈕扣。（引申用法 unbuttoned 也可形容人放鬆下來、不再拘謹。）
原始詞典資料2 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
unbuttonverb/ʌnˈbʌtən/
- 1
To open (something) by undoing its buttons.
- Being now too high wound up to bear a delay, he unbutton'd, and drawing out the engine of love-assaults, drove it currently, as at a ready-made breach
- "Mr Baxter, I think?" said the latter. He had laid aside his dripping umbrella and was unbuttoning overcoat and coat to reach an inner pocket.
- 2
To come open by having its buttons unfastened.
- He was so muscled and firm, and the canvas shirt under his jacket unbuttoned easily.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。