Merchant Definition

Wholesaler or retailer who may buy goods from any or all sources for resale to anyone and everyone for profit. In law, a merchant is held to a higher standard of duty of care than a non-merchant because he or she is deemed to have expert knowledge about the goods he or she deals in.

Source: Businessdictionary

According to Wikipedia..

In the United States, "merchant" is defined (under the Uniform Commercial Code) as any person while engaged in a business or profession or a seller who deals regularly in the type of goods sold. Under the common law and the Uniform Commercial Code in the United States, merchants are held to a higher standard in the selling of products than those who are not engaged in the sale of goods as a profession. For example, when a merchant sells something, he or she is deemed to give an implied warranty of merchantability, guaranteeing that the product is fit to be sold, even if there is nothing in writing to this effect. The UCC also contains a "merchant's confirmation" exception to the Statute of Frauds.

Source: wiki