My dictionary says that trade in is completely an American word and has American meaning and means:
to give (a used article) as payment to be credited toward a purchase: We trade in our car every three years.
[quoted from dictionary.com]
Do we have trade in in English language?
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American English is a major part of the English language. The Cambridge Advanced Learner’s Dictionary does not indicate the American bias:
[i]Trade-in noun [C]
a method of buying something new by giving an item you own as part of the payment for it:
We got a good trade-in price for our old television.[/i]
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