customer

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One that buys goods or services, as from a store or business.
• noun Informal An individual with whom one must deal.

from The Century Dictionary.

• noun A collector of customs; a toll-gatherer; a tax-gatherer.
• noun One who purchases goods or a supply for any current need from another; a purchaser; a buyer; a patron, as of a house of entertainment.
• noun A prostitute.
• noun One who has special customs, as of the country or city.
• noun Any one with whom a person has to deal; especially, one with whom dealing is difficult or disagreeable; hence, a fellow: as, a queer customer; a rough customer.
• Being a customer or customers; purchasing; buying.
• Made to the order of or for a customer; specially ordered by a customer and made for him: opposed to ready-made, or made for the market generally: as, customer work.

from the GNU version of the Collaborative International Dictionary of English.

• noun obsolete One who collect customs; a toll gatherer.
• noun One who regularly or repeatedly makes purchases of a trader; a purchaser; a buyer.
• noun A person with whom a business house has dealings.
• noun colloq. A peculiar person; -- in an indefinite sense.
• noun obsolete A lewd woman.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A patron; one who purchases or receives a product or service from a business or merchant, or intends to do so.
• noun informal A person, especially one engaging in some sort of interaction with others.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun someone who pays for goods or services