A stomachache is a pain in your stomach or the area around it. In real use, English speakers use it loosely for almost any pain in the middle of the body — from eating too much, from bad food, from period pain, or from nerves before an exam. Doctors may be more exact, but ordinary people are not.

A stomachache一個stomachache（肚子痛） is a pain in your stomach就是你胃部 or the area around it或附近區域的一種疼痛。In real use實際使用上 English speakers use it loosely英語使用者用得很鬆散 for almost any pain in the middle of the body幾乎身體中段任何的痛都可以用 from eating too much可能是吃太多 from bad food可能是吃壞東西 from period pain可能是經痛 or from nerves before an exam或是考試前緊張。Doctors醫生 may be more exact可能會講得比較精確 but ordinary people are not但一般人不會

Two grammar points matter more than the meaning here. First, in American English it is usually written as one word, stomachache; in British English you often see two words, stomach ache. Both are correct.

Two grammar points有兩個文法重點 matter more than the meaning here在這裡比意思本身還重要。First第一 in American English在美式英文裡 it is usually written as one word通常會寫成一個字 stomachachestomachache in British English而在英式英文裡 you often see two words常常會看到兩個字 stomach achestomach ache。Both are correct兩種寫法都對

Second, and this catches everyone: it takes 'a'. You say 'I have a stomachache', not 'I have stomachache' — though British speakers do sometimes drop the 'a', which is why students see both and get confused. Follow the 'a'.

Second第二 and this catches everyone這一點大家都會不小心錯 it takes 'a'它要加'a'。You say你要說 'I have a stomachache'「I have a stomachache」 not 'I have stomachache'而不是「I have stomachache」 though British speakers do sometimes drop the 'a'不過英國人有時候確實會把'a'省略掉 which is why students see both and get confused這就是為什麼學生兩種都看過、搞不清楚的原因。Follow the 'a'照著加'a'就對了

It is an everyday word, fine to say to a friend, a teacher, or a doctor. It usually means something mild and temporary; for something serious, people say 'stomach pains' or name the real problem.

It is它是 an everyday word一個日常用詞 fine to say to a friend, a teacher, or a doctor跟朋友、老師，或醫生說都沒問題。It usually means它通常指的是 something mild and temporary一種輕微、暫時的不舒服 for something serious如果是嚴重的狀況 people say 'stomach pains'大家會說'stomach pains' or name the real problem或是直接說出真正的問題