Etymological dictionaries focus specifically on tracing the origins and evolution in words and word meanings. Subject dictionaries list and define words used in a specific discipline, profession, or area of specialized knowledge. Foreign language dictionaries list and define words in languages other than English. Bilingual dictionaries match words in one language with their equivalents in another. Usually, one of the languages is English.
Polyglot dictionaries list equivalent words in three or more languages.
Directory A list of persons, or of businesses or other types of organizations . Directories of other types of organizations also list officers, and well as function or purpose of the organization. Encyclopedia A book or set of books containing informational articles on a variety of subjects, usually arranged in alphabetical order. General encyclopedias include articles providing information from virtually every field of human knowledge. Specialized or subject encyclopedias focus on a specific discipline or field of study.