To help you out here is a common list of terminology used when purchasing a mailing list:
Business Mailing List - A compiled mailing list of businesses. Typical selections include geography, type of business, revenue, number of employees.
Compiled List - Any direct mail list created from the compilation of public sources such as phone books, deed information, directories, newspapers and courthouse records.
Consumer Mailing List - A compiled mailing list of consumers. Typical selections include geography, income, age, homeowner/renter, children present in household.
Counts - The number of addresses that fit your selection criteria.
House List - A mailing list compiled of those who have previously purchased from your own company. This would be your customer base.
List Selection - Using criteria such as age, income, homeownership etc to create a targeted mailing list.
List Cleaning - The process of updating a mailing list by correcting and/or removing a name because it is no longer correct.
Merge-Purge - Combining two or more mailing lists while simultaneously eliminating duplicate names.
Occupant Mailing List - These inexpensive lists are perfect when you want to saturate a market of any size. Occupant Lists include all the addresses in a geographic area. The occupant mailing list you order will contain the address, city, state, and ZIP+4 but not the name. The files are addressed to Current Resident.
One Time Use Mailing List - Unless specified otherwise, most mailing list rentals are for a single use. It is understood that the mailer will not use the names on the direct mail list more than one time without prior approval of the mailing list owner.
Sample Mail Piece - Some direct mailing list owners require submission of a sample prior to agreeing to rent their mailing list. This not required for compiled mailing lists but often required for specialty mailing lists.
Specialty Mailing List - non compiled mailing lists such as lists of subscribers to a magazine, or health club members. Specialty mailing lists often cost considerably more than compiled lists but often allow for a more targeted mailing.