Dictionaries contain brief descriptions of a word or concept, and provide standards for its spelling and usage. They can be comprehensive, or technical, for example, limited to a subject or language.
Thesauri provide synonyms and antonyms for words and phrases, which often can help you to refine word choice when writing, or target better terms for information-seeking during research.
Dictionaries and thesauri often contain additional information, such as word histories and examples of proper grammar. The online versions often have add-ons for your web browser for quick lookups, bookmarking and more.
This page provides only a partial listing of the dictionaries available through UC San Diego. To find specialized ones for a country, topic or discipline, use the following technique:
Example: archaeology dictionaries