Reverse dictionary

A reverse dictionary is a dictionary organized in a non-standard order (usually referring to being in a so-called "reverse" order) that provides the user with information that would be difficult to obtain from a traditionally alphabetized dictionary. There are two principal types of reverse dictionaries: reverse word dictionaries, and reverse concept dictionaries (conceptual dictionary). This article discusses reverse word dictionaries; see conceptual dictionary for reverse concept dictionaries.

Reverse dictionaries were historically difficult to produce before the advent of the electronic computer, but have become more common since 1974, when the first computer sorted reverse dictionary was published: Stahl and Scavnicky's A Reverse Dictionary of the Spanish Language.

The reverse word dictionary is a dictionary where the word entries in the dictionary are not alphabetized in the same manner as a traditional dictionary. For example, A Reverse Dictionary of the Spanish Language and Walker's Rhyming Dictionary are reverse dictionaries, the organization of which is based upon sorting each entry word upon its last letter and the subsequent letters proceeding toward the beginning of that word. Consequently, in these reverse dictionaries all words that have the same suffix appear in order in the dictionary. Such a reverse dictionary would be useful for linguists and poets who might be looking for words ending with a particular suffix, or by an anthropologist or forensics specialist examining a damaged text (e.g. a stone inscription, or a burned document) that had only the final portion of a particular word preserved. Reverse dictionaries of this type have been published for most major alphabetical languages (see numerous examples listed below). By way of contrast, in a standard dictionary words are organized such that words with the same prefix appear in order, since the sorting order is starting with the first letter of the entry word and subsequent letters proceeding toward the end of that word.

Applications of reverse word dictionaries include:

Reverse word dictionaries are straightforward to construct, by simply sorting based on reversed words. This was labor-intensive and tedious before the advent of electronic computers, but is now straightforward. For example, using Perl and sort allows the following one-liner program to produce a reverse dictionary of the file "dict":

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