Longman Dictionary of Contemporary English
Wiktionary
n. A system of commerce in which one orders goods from a remote store which are then shipped by mail.
WordNet
n. a purchase negotiated by mail
Wikipedia
Mail order is the buying of goods or services by mail delivery. The buyer places an order for the desired products with the merchant through some remote method such as through a telephone call or web site. Then, the products are delivered to the customer. The products are typically delivered directly to an address supplied by the customer, such as a home address, but occasionally the orders are delivered to a nearby retail location for the customer to pick up. Some merchants also allow the goods to be shipped directly to a third party consumer, which is an effective way to send a gift to an out-of-town recipient.
A mail order catalogue is a publication containing a list of general merchandise from a company. Companies who publish and operate mail order catalogues are referred to as cataloguers within the industry. Cataloguers buy or manufacture goods then market those goods to prospects (prospective customers). Cataloguers may "rent" names from list brokers or cooperative databases. The catalogue itself is published in a similar fashion as any magazine publication and distributed through a variety of means, usually via a postal service and the internet.
Sometimes supermarket products do mail order promotions, whereby people can send in the UPC plus shipping and handling to get a product made especially for the company.
Usage examples of "mail order".
Tried to get him malpractice insurance they drag out some yellow newspaper clippings ten years ago in Kansas same God damn thing, thirteen year old kid comes in for counseling and Ude has him reading the Bible listening to taped sermons and tells him he's a sinner puts the fear of God in him the kid goes home and hangs himself, family's Roman Catholic they sue for negligence wrongful death same list right down the line, telling everybody Ude's a mail order minister someplace in Modesto California ordains ten million of them a year to swindle the IRS any smear they can think of, all hearsay any smear they can think of.