Underclothes are the clothes you wear right against your skin, under everything else — underpants, bras, vests, undershirts. The word is always plural: you say 'my underclothes are wet', never 'an underclothe'. To count them you need another word: 'a pair of underpants', 'two items of underwear'.

Underclothes內衣褲 are the clothes you wear right against your skin是直接貼著皮膚穿的衣物, under everything else穿在所有衣服最裡面 — underpants, bras, vests, undershirts像內褲、胸罩、背心、貼身內衣。 The word is always plural這個字永遠是複數: you say你會說 'my underclothes are wet'「my underclothes are wet」, never 'an underclothe'絕不會說「an underclothe」。 To count them要數它們的數量 you need another word得用別的字: 'a pair of underpants'「一件內褲」, 'two items of underwear'「兩件內衣物」。

In real speech, most people say 'underwear' — that is by far the commonest word today, and it works as a singular uncountable noun, so 'my underwear is in the wash' is fine. 'Underclothes' sounds slightly older and slightly more careful, the kind of word a parent packing a suitcase might use, or a hospital form.

In real speech在實際口語裡, most people say大多數人會說 'underwear'「underwear」 — that is by far the commonest word today這是現在最常用的字, and it works as a singular uncountable noun而且它是單數不可數名詞, so 'my underwear is in the wash' is fine所以「my underwear is in the wash」是對的。 'Underclothes'這個字聽起來 sounds slightly older and slightly more careful稍微老派一點、也稍微講究一點, the kind of word a parent packing a suitcase might use像是家長在打包行李箱時會用的字, or a hospital form或是出現在醫院表格上。

'Undies' is the playful, casual version; 'lingerie' (from French) means women's underwear that is meant to look beautiful, and sounds either fancy or suggestive depending on who is speaking; 'smalls' and 'underthings' are older British words you may meet in books. Note also 'underclothing', which is uncountable and even more formal.

'Undies' is the playful, casual version「undies」是the playful（俏皮）, casual（隨性）version（講法）; 'lingerie' (from French)「lingerie」（來自法文） means women's underwear that is meant to look beautiful指的是講究美觀的女性內衣, and sounds either fancy or suggestive depending on who is speaking聽起來可能高雅、也可能有點曖昧，要看是誰在講; 'smalls' and 'underthings'「smalls」和「underthings」 are older British words you may meet in books則是你可能在書裡遇到的老派英式說法。 Note also另外還有 'underclothing'「underclothing」這個字, which is uncountable and even more formal是不可數、而且更正式的講法。

Because underwear is a slightly private topic in English-speaking cultures, people often use these words in a quick, matter-of-fact way rather than dwelling on them.

Because underwear is a slightly private topic in English-speaking cultures因為在英語文化裡內衣是稍微私密的話題, people often use these words in a quick, matter-of-fact way人們講到這些字時通常簡短、平淡帶過 rather than dwelling on them而不會多加著墨。