A book containing the words of a language, arranged alphabetically, with explanations of their meanings; a lexicon; a vocabulary; a wordbook.
- A reference book containing an alphabetical list of words, with information given for each word, usually including meaning, pronunciation, and etymology.
- A book listing the words of a language with translations into another language.
- A book listing words or other linguistic items in a particular category or subject with specialized information about them: a medical dictionary.
- Computer Science A list of words stored in machine-readable form for reference, as by spelling-checking software.
- Computer Science An electronic spelling checker.