The piece of clothing you wear to swim in. In everyday use it usually means a woman's or girl's one, and most often the one-piece kind that covers the body — that is the picture most people get first.

The piece of clothing you wear to swim in游泳時穿的衣服。In everyday use日常用法裡 it usually means a woman's or girl's one通常是指女生穿的那種，and most often the one-piece kind that covers the body而且大多是包住身體的連身式，that is the picture most people get first這是大多數人腦中先浮現的畫面。

For men, English speakers usually say swimming trunks, swim shorts, or just trunks instead.

For men男生的話 English speakers usually say swimming trunks, swim shorts, or just trunks instead英語人士通常會改說swimming trunks、swim shorts，或直接說trunks。

There are lots of regional words here, which is why students get confused: British speakers often say swimming costume or cossie, older speakers might say bathing suit (still very common in America), and 'bikini' is the specific two-piece. 'Swimsuit' is the safest, most neutral word of the lot, understood everywhere.

There are lots of regional words here這裡有很多地區性的說法，which is why students get confused這也是學生容易搞混的原因：British speakers often say swimming costume or cossie英國人常說swimming costume或cossie，older speakers might say bathing suit年紀較大的人可能會說bathing suit（still very common in America在美國仍然很常用），and 'bikini' is the specific two-piece而'bikini'則專指兩件式的泳裝。'Swimsuit' is the safest, most neutral word of the lot'swimsuit'是這些說法裡最安全、最中性的，understood everywhere到哪裡都聽得懂。

Note that it is one word, no space, and it is countable: a swimsuit, two swimsuits.

Note that it is one word, no space注意這個字是一個單字、中間沒有空格，and it is countable而且是可數名詞：a swimsuit, two swimsuits一件swimsuit、兩件swimsuits。

In Taiwan you will meet it on shop signs and at every pool, often next to the rule that a swimming cap is required too.

In Taiwan在台灣 you will meet it on shop signs and at every pool你會在店家招牌和每個游泳池看到這個字，often next to the rule that a swimming cap is required too常常旁邊還寫著也規定要戴泳帽。