Dictionary is a reference book containing an alphabetical list of words, with information given for each word, usually including meaning, pronunciation, and etymology.
Modern dictionaries can be categorized into:
1. General dictionaries
2. Specialized dictionaries (e.g. medical, legal)
3. Bilingual dictionaries
4. Electronic dictionaries
The word "dictionary" first appeared in the 16th century, derived from Medieval Latin "dictionarium".