廁所
在美國一般都叫rest room或bath room(男女廁均可)或分別叫做 men‘s room 或 ladies‘ room(=powder room)，不過在飛機上，則叫 lavatory，在軍中又叫 latrine。至于 W.C.(water closet)仍是過去英國人用的，在美國，幾乎沒有人使用。
解小便
最普通的說法是 to urinate(名詞是 urination)，如果去看病，護士為了化驗小便，就會給你一個杯子說：「Will (could) you urinate in this cup?」醫生或許也會問：「Do you have trouble urinating?」=Do you have difficulty voiding?(小便有困難嗎?)
此外，還有其他的說法：to piss = to take a piss = to take a leak = to void = to empty。 例如：
* I need to piss = I have to take a leak.
* How often do you get up at night to void?(晚上起床小便幾次?)
此外，john(j 小寫時，不是男人名字)是 bath room 或 toilet 的意思(也叫 outhouse)，這通常是指在戶外工作場地所使用的臨時或流動性廁所(有時前面也加 portable 一字)。不過也有老外把家里的廁所叫做 john。 例如：
* There are several (portable) johns in the construction site.(在建筑場地有幾個臨時廁所。)
* He went to the john a few minutes ago.(他在幾分鐘前上了廁所。)
* The manual labours have to use (portable) johns during their working hours.(勞動者在工作時間內需要使用流動性廁所。)
不過，小孩多半用 to pee 。例如：
* The boy needs to pee.
然而，「小便檢查」又叫做 urine test，因為這里的 urine 是化驗的樣品(specimen)。 例如：
* Do I need a urine test?
注意：to piss off 是片語，又是指對人生氣或對事物的不滿。不過這是不禮貌的片語，少用為妙。 例如：
* He pissed me off. = He made me angry.
* He always pisses off (at) the society.(對社會不滿)
如果「小便」有毛病，也可以告訴醫生說：
* My urine is cloudy and it smells strong.(有濁尿，味道很重)
* I have pus (或air)in urine.(尿有泡沫) (pus = cloudy; air = bubble)
* I dribble a little urine after I have finished urinating.(小便后還會滴滴答答。)(即失禁毛病)
* I am passing less urine than usual.(小便的量比平時少)
解大便
一般是用 to make(或 have)a bowel movement 或 to take a shit。如果看病，醫生常問：「Do you have regular bowel movement?」(大便正常嗎?)(說得斯文些，就是「大腸在轉動」)
此外，還有其他的說法： to defecate =to discharge excrement(或 feces)=to take feces (或 faeces)。 例如：
* The patient needs to take a shit. (=to make a bowel movement)
不過，小孩多半是用 to make a poo poo 或 to make a BM. 。 例如：
* The boy had a stinky BM.(大便奇臭。)
但是「大便檢查」倒叫做 stool exam，因為 stool 也是一種化驗的樣品。 例如：
* The doctor has to exam his stool.(醫生要檢查他的大便。)
放屁
在美語里最常用的是 to expel gas 或 to fart 或 to make (或 pass)gas。 例如：
* 醫生有時問：「How often do you expel(或 make 或 pass)gas?」(你放屁的次數很多嗎?)
* Is the gas expelled by belching?(是否打嗝后就會放屁呢?)(動詞是 belch)
* He said the more he ate, the more he farted.(吃的愈多，放屁也愈多。)
* He has passed more gas than usual within the last two days.(過去兩天中，他放屁比平常多。)
* Be careful not to fart in the public.(注意在公共場所不可放屁。)
至于消化不良，大便不通或拉肚子，也有不同的說法。 例如：
* I have an upset stomach.(消化不良) = I have heartburn. = I have indigestion.
(注意：Heartburn 是指胃不舒服，不是「心痛」(heartache)
* Something has upset my stomach for two weeks.(胃不舒服有兩星期了。)
* He has(persistent)constipation.(或 irregularity)(他經常便秘。) 或
* He has been unusually constipated.(便秘很反常。)或
* He is having problem with irregularity.(或 constipation); 或
* He has no bowel movement for the past few days.
* He has bouts of diarrhea.=He is having trouble with diarrhea.(他拉了一陣肚子。)
* He can see trace of blood and pus or mucus in his stool(或 bowel movement)(大便時可看到血絲和粘膜。)
