第三者

One of my Ss asked me a question...... 
( S = my student; Y = me )
S: What's the English for the Chinese " ²Ä¤TªÌ "? 
Y: I'm not sure are there any vocabularies or phrases for " ²Ä¤TªÌ " in English but you can explain the meaning of " ²Ä¤TªÌ " to your friends. In chinese, it means someone who gets involved with someone who's already in a relationship.
S: That's too complex! You can say " the third person ". 
Y: Well, I think that's pidgin English. It doesn't really have that meaning in English.... 
S: No kidding! See, I'm reading this English book by Jolin Tsai.
Y: I see. Anyway, Jolin Tsai says that " the third person " is the right way to say it in English.
 
And then I asked 3 of my coworkers....
C1: A relationship is between 2 people. If a third person gets involved it is called a " love triangle ". England they would call the third person a " bounder ". " Adultery " is a word that means that the 2 people of the " love triangle " were married. The proper meaning of " third person " is a literary term. It is used when describing a stroy about 2 other people, " spoken in the third person ".
C2: In most case I may hear of " the other woman " or " the other man " and these are the nicest term I would hear about a third person secretly getting invloved with someone in a relationship. And of course when there are three who willingly have sexual relationship experience at the same time many use the French term " menage a trois " or in American slang, a three way.
C3: She's totally wrong. I guess she didn't have an eidtor. What qualifies her to write about English, anyway?
Y: Hummm.... I think she studied English in college...?!
C3: Oh really? I studied Chinese in college, but I wouldn't even think about writing a book on it.
Y: Well, Taiwan's publishing industry is just like that. Famous people can get stuff out, even if it's not good.