Encyclopedias

Encyclopedia of Business and Finance, Burton S. Kalinski.  Macmillan Reference, 2nd, ed., 2007.
Online through Gale Virtual Reference Library.
Print in Ford Library Reference HF1001 .E466 2007
Older edition in Perkins/Bostock Reference HF1001 .E467 2001

This two-volume encyclopedia has relatively short summary articles written by academics and professionals in the field.  Most articles include bibliographies for further reading.  This is the standard introductory encyclopedia in a field without many; most business encyclopedias cover a specific subfield.

Encyclopedia of Business Information Sources, Gale Research, updated annually.
Current year at Perkins/Bostock Reference Desk HF1007 .E539

This bibliographic reference encyclopedia is arranged alphabetically by (very detailed) topic (macaroni, machine design, machine shops...), with subdivisions by type of resource (directory, dictionary, online database).  The 35,000 entries are short and do not include annotations.  Includes contact information for trade associations and titles of trade journals, as well as sources of information for commodity prices and financial statements.

Dictionaries

A Dictionary of Business and Management, Oxford University Press, 4th ed., 2006.
Available online at Oxford Reference Online
Perkins/Bostock Reference HF1001 .C63 2006 

A standard reference for short definitions of business terms and concepts, with heavy cross-referencing. There is a British/European bias, despite international coverage.   

The Economist Dictionary of Business, Graham Bannock, 2002.
Perkins/Bostock Reference HF1001 .B366 2002

In addition to definitions of terms and concepts, includes some short biographies of economists.  Also has a UK bias.

Longman Business English Dictionary, Longman, 2000.
Perkins/Bostock Reference HF1001 .L664 2000

This dictionary includes 20,000 words and phrases and has pronounciation guides in addition to definitions.  Includes both British and American English terms with notations to distinguish them. 

Understanding American Business Jargon: A Dictionary, W. Davis Folsom, Greenwood Press, 2nd ed., 2005.
Perkins/Bostock Reference HF1001 .F65 2005

This is more geared toward the clarification of jargon and popular business metaphors than the definition of terms or concepts; as a result, entries are quite short.  As the title indicates, it is American in focus.  As many of the phrases covered have entered popular discourse, this dictionary might be especially useful for non-Americans and/or non-native speakers of English.