To give a piece of merchandise as part of the payment or trade for something new.

property used as part payment for a new purchase / a transaction including such payment

(idiomatic) As a profession; professionally.

present participle of trade in

Third-person singular simple present indicative form of trade in

Full of trade; busy with commerce.

simple past tense and past participle of trade in

(Ireland, Britain) The sale of alcoholic drinks for consumption on the premises.

(uncountable) Buying and selling of goods and services on a market. / (countable) A particular instance of buying or selling. / (countable) An instance of bartering items in exchange for one another.

Of a product, produced for sale in the ordinary bulk retail trade and hence of only the most basic quality.