Encyclopedia

An encyclopedia or encyclopaedia  is a reference work or compendium providing summaries of knowledge either from all branches or from a particular field or discipline. Encyclopedias are divided into articles or entries that are often arranged alphabetically by article name  and sometimes by thematic categories. Encyclopedia entries are longer and more detailed than those in most dictionaries. Generally speaking, unlike dictionary entries—which focus on linguistic information about words, such as their etymology, meaning, pronunciation, use, and grammatical forms—encyclopedia articles focus on factual information concerning the subject named in the article's title.