A polygraph is a machine the police (and sometimes a boss) use when they want to know if someone is telling the truth. It does not read thoughts. While a person answers questions, it writes down several body signs at the same time — heart, breathing, and sweat on the skin — as lines on paper or on a screen. The hope is that a lie will make the body jump a little, and the lines will show it.

A polygraph一台 polygraph is a machine the police use是警察會用的一種機器 and sometimes a boss有時候老闆也會用 when they want to know if someone is telling the truth用來判斷一個人講的是不是實話 It does not read thoughts它不會讀心 While a person answers questions當一個人在回答問題的時候 it writes down several body signs at the same time它會同時記錄好幾種身體反應 heart, breathing, and sweat on the skin心跳、呼吸，還有皮膚上的汗 as lines on paper or on a screen畫成紙上或螢幕上的線條 The hope is that a lie will make the body jump a little希望是說謊會讓身體有一點小小的反應 and the lines will show it而那些線條會顯示出來

Poly- is 'many' and -graph is 'write', so it is a 'many-writing' machine: many lines at once. That is also why people nicknamed it a lie detector.

Poly- is 'many' Poly- 是「很多」的意思 and -graph is 'write'而 -graph 是「寫」的意思 so it is a 'many-writing' machine所以這是一台「寫很多東西」的機器 many lines at once同時畫出好幾條線 That is also why people nicknamed it a lie detector這也是為什麼大家把它戲稱為測謊機

Though actually, the tidy story and real life do not match well. Being afraid, angry, or just shy can move those lines too, and many scientists say the machine cannot really pick a lie out from that. Some places still use it; some courts will not trust it.

Though actually不過其實 the tidy story and real life do not match well這個聽起來乾淨俐落的說法跟現實不太吻合 Being afraid, angry, or just shy害怕、生氣，或只是害羞 can move those lines too也都可能讓那些線條跟著動 and many scientists say the machine cannot really pick a lie out from that所以很多科學家認為這台機器沒辦法真的從中分辨出謊言 Some places still use it有些地方還是會用它 some courts will not trust it有些法院則不採信

In films it is a truth machine. In the real world it is a tool people argue about.

In films在電影裡 it is a truth machine它是一台講真話的機器 In the real world在現實世界裡 it is a tool people argue about它是一個大家還在爭論的工具

You can also use it as a verb: to polygraph someone is to put them on that machine.

You can also use it as a verb你也可以把它當動詞用 to polygraph someone polygraph 一個人 is to put them on that machine就是讓他接受這台機器的測試

There is an older, rarer sense too — a machine that copies writing, or a person who writes a lot — same pieces of the word, different job. When people say polygraph now, they almost always mean the police test.

There is an older, rarer sense too還有一個比較古老、少見的意思 a machine that copies writing指一種複製書寫內容的機器 or a person who writes a lot或是指一個寫很多東西的人 same pieces of the word用的是同樣的字根 different job但做的是不同的事 When people say polygraph now現在大家講 polygraph 的時候 they almost always mean the police test幾乎都是指警方那種測謊測試