A trader is a person whose work is buying and selling. The word covers two quite different working lives, and students often only meet one of them.

The older, plainer sense is someone who sells goods. A market trader stands behind a table of fruit or phone cases. A trader in an old story sails between ports with silk and spices. In British English this sense is still very much alive — "market traders", "street traders", "a small trader" meaning a small shopkeeper or businessperson.

The newer sense, the one you see in the news, is someone who buys and sells stocks, currencies, or other financial things, usually for a bank or for themselves. This person sells nothing you can hold. They sit at a desk with several screens. "He works as a trader in Taipei" almost always means this now, unless the situation makes the market-stall meaning obvious.

A trader is not the same as a shop owner, though one person can be both. The word points at the activity — the buying and the selling — rather than at owning a place. And a trader is usually a person, or a small business acting like one; a big company is called a company, not a trader.

The word feels neutral. It carries neither the respect of "businessman" nor the suspicion of "dealer". Though actually, "trader" can lean slightly toward hard-headedness — someone who is in it for the margin, not for the love of the goods.