dictionary

Pluraldictionaries

Formsdictionaries, dictionarying, dictionaried

1. 1
   word booknouncountable

   A reference book, website or app that lists words, usually alphabetically, giving their meanings or equivalents in another language and often spelling, pronunciation and origins; also seen as the authority on which words are proper.

   She reached for the dictionary to check the spelling of a tricky word.

   The library keeps several dictionaries from different centuries on display.

   UsageYou look a word up in a dictionary, or check it in the dictionary.

2. 2
   subject referencenouncountable

   A reference work covering a single subject or activity, with its entries arranged alphabetically; essentially an alphabetical encyclopedia.

   Her dictionary of architecture runs from 'abacus' to 'ziggurat,' with a drawing for nearly every entry.

   Scholars often consult specialized dictionaries before writing about an unfamiliar field.

   UsageThe field goes before the noun or after of: a law dictionary, a dictionary of architecture.

   Similarencyclopedia, glossary, lexicon

   Note

   Here the alphabet organizes a field rather than a language: a law dictionary, a dictionary of sports. What separates it from the general word-book is scope. It explains the terms and things of one field, which is why it shades so easily into an alphabetical encyclopedia.

3. 3
   nouncountablecomputing

   A saved list of words or terms that software compares text with, for example to check spelling, complete words, or guess passwords.

   Add technical terms to the spell checker's custom dictionary so they stop getting flagged.

   Passwords made of ordinary words fall quickly to an attack that runs through a large dictionary.

   UsageCommon in a custom dictionary and a dictionary attack.

   Note

   Software keeps the name even though nothing is defined: what matters is only whether a string is on the list. Spell checkers let users add words to a custom dictionary, and in security a dictionary attack tries likely passwords from such a list instead of every possible combination. Programmers should keep it apart from the key-value data structure, which shares the name but stores pairs. Source

   Checked 30 Oct 2026 · 5 facts

   • A software dictionary can contain a word list without definitions. aspell.sourceforge.net
   • Membership in a custom spelling dictionary determines whether a word is accepted. support.microsoft.com
   • Spell checkers allow users to add words to custom dictionaries. support.microsoft.com
   • A dictionary attack tests passwords drawn from a dictionary rather than exhaustively testing every possible combination. capec.mitre.org
   • The programming data structure called a dictionary stores keys paired with values. docs.python.org
4. 4
   source of knowledgenounfigurativelycountable

   Someone or something seen as a rich store or comprehensive source of information.

   Her mentor was a living dictionary of courtroom procedure.

   To the young crew, the old harbor master was a walking dictionary of tides, wrecks, and local lore.

   UsageUsually a walking dictionary or a living dictionary of a subject.

   Similarencyclopedia, storehouse, repository

5. 5
   vocabularynouncountablewith ofpossessive

   The whole collection of words that a particular person knows or uses; their vocabulary.

   The critic sneered that the politician's entire dictionary consisted of slogans.

   Words like compromise and patience simply did not exist in the general's dictionary.

   UsageMostly in the frame not in someone's dictionary: quit is not in my dictionary.

   Similarvocabulary, lexicon

6. 6
   data structurenouncountable

   A data structure in which each value is stored and retrieved by a unique key, much like words paired with definitions in a printed dictionary.

   Like a phone book that hands you a number the moment you know the name.

   The function returns a dictionary mapping each country to its capital city.

   Python dictionaries store key-value pairs and allow fast lookups.

   Similarmap

   Note

   Programmers borrowed the word for a structure that pairs each key with a value, the way a headword is paired with its definition. Associative array names the same idea. Values are found by key rather than by position, and typical hash-based implementations make that lookup fast on average. The noun takes of for its contents: Professional ASP.NET MVC 3 (2011) passes "a dictionary of values" to a routing method. Source

   Checked 30 Oct 2026 · 6 facts

   • The computing name reflects the analogy between key–value pairs and words paired with definitions. infx511.github.io
   • An associative array is also called a dictionary. docs.python.org
   • Dictionary values are retrieved using keys. docs.python.org
   • Hash-based dictionaries typically provide fast lookup. learn.microsoft.com
   • Professional ASP.NET MVC 3 was first published in 2011. oreilly.com
   • The book uses the exact phrase “a dictionary of values” when describing arguments passed to RouteCollection.GetVirtualPath. en.wiktionary.org

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