Skip to Main Content


Page 3



Dictionaries are used to find information about words or terms. If you are unfamiliar with the terminology associated with your research topic, consult a dictionary.

Dictionaries contain lists of words arranged in alphabetical order, giving the definition, origins, and spelling of each word. Depending on the dictionary's size and scope, they may also provide pronunciation, usage, synonyms, and antonyms, and/or trace the changes in the meaning and usage of a word over time.

There are two basic types of dictionaries:

  • Unabridged dictionaries are the largest dictionaries, containing 400,000 to 650,000 words. They try to include every word in the language. An unabridged dictionary is a good place to look for the meaning of an obscure word that doesn't appear in a smaller dictionary. Examples of an unabridged dictionary include The Oxford English Dictionary and Webster's Third New International Dictionary. In addition to the print version, the Library subscribes to the Oxford English Dictionary Online.
  • Abridged dictionaries limit themselves to the more commonly used words. They are often called desk, collegiate, or shortened dictionaries. Many students are most familiar with this type of dictionary, using it to check words when studying or writing papers. Examples of an abridged dictionary include American Heritage Dictionary and Merriam Webster's Collegiate Dictionary, 11th Edition.

Subject dictionaries provide definitions or short explanations of the terms and concepts used in a specific discipline or field.

collage of covers from subject dictionaries

For example, when researching space stations, you might encounter unfamiliar terms such as "geostationary satellite" Use a subject dictionary like the Mc-Graw-Hill Dictionary of Scientific and Technical Terms to find definitions for such terms, and to identify related terms.

dictionary entry for geostationary satellite 
McGraw-Hill Dictionary of Scientific and Technical terms
Chapter 3 — Page 3