1
a waistcoat
waistcoat 是可数名词，常用不定冠词 a 表示一件。
He bought a waistcoat.
他买了一件马甲。
马甲；西装背心
先理解核心含义，再看它在真实句子里的用法。
马甲；西装背心
waistcoat
He bought a waistcoat.
他买了一件马甲。
穿在紧身上衣内的装饰性服装。
An ornamental garment worn under a doublet.
马甲:男人穿在外套里面的无袖衣服
a man's sleeveless garment worn underneath a coat
He wore a dark blue waistcoat under his suit jacket to the job interview.
他西装外套里面穿了一件深蓝色马甲，去参加求职面试。
The tailor is sewing a small pocket onto the grey waistcoat.
裁缝正在灰色马甲上缝一个小口袋。
These wool waistcoats are warm and can be worn over a shirt.
这些羊毛马甲很暖和，可以穿在衬衫外面。
waistcoat 是可数名词，常用不定冠词 a 表示一件。
He bought a waistcoat.
他买了一件马甲。
wear 的过去式是 wore；这个结构表示‘穿着马甲’。
He wore a waistcoat to the meeting.
他穿着马甲去开会。
这个结构直接对应字典释义：马甲是穿在外套内的无袖衣物。
A waistcoat is worn underneath a coat.
马甲穿在外套里面。
Not this
He wore waistcoat to the interview.
Use this
He wore a waistcoat to the interview.
waistcoat 是可数名词，单数形式前必须有冠词等限定词；汉语中没有冠词，学习者容易漏掉 a，因此应说 a waistcoat。
Not this
I posted under my waistcoat account.
Use this
I posted under my sockpuppet account.
汉语网络语中的“马甲”可指隐藏身份的小号，但英语 waistcoat 只指服装。表达“马甲账号”时要用 sockpuppet 或 alternate account，不能把汉语的词义直接套用到 waistcoat 上。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
穿马甲；穿西装背心
He wore a grey waistcoat under his jacket.
他在夹克里面穿了一件灰色马甲。
马甲口袋；背心口袋
She kept her watch in her waistcoat pocket.
她把表放在马甲口袋里。
条纹马甲
The groom wore a striped waistcoat with his morning suit.
新郎穿着晨礼服，配了一件条纹马甲。
刺绣马甲
The traditional costume includes an embroidered waistcoat.
这套传统服装包括一件刺绣马甲。
白兔从它的马甲口袋里拿出一块怀表。
He wore a brown waistcoat over a crisp white shirt.
他在挺括的白衬衫外面穿了一件棕色马甲。
Use waistcoat naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
联想 waist（腰）+ coat（外套）：像给腰部穿的外套，无袖，就是马甲/西装背心。
语域：mixed 常见场景：tailor's shop、suit fitting、formal event、historical drama 该词通常用于正式着装或英式英语语境，如西装背心、三件套等；正式度随地区或语境有变化，美式英语中偏传统或正式，日常中也常听到 vest 的说法。
The first part of 'waistcoat' is pronounced /weɪst/, the same as 'waste' — 'waist' and 'waste' are homophones but have different meanings. The final syllable is /kəʊt/, matching the ending of 'raincoat' and the single-syllable words 'coat', 'boat', and 'goat'. However, in 'waistcoat' and 'raincoat' the stress is on the first syllable, so they do not rhyme strictly with the stressed one-syllable words 'coat', 'boat', and 'goat'. Be careful not to confuse the spelling of 'waist' with 'waste'.
Dictionary facts from ECDICT, WIKTIONARY.