Artha is a cross-platform and open source thesaurus and dictionary based on WordNet that works completely off-line. Artha can define not only English word, but even proper nouns i.e. famous personalities, places, events, phrases, acronyms, slangs - to list a few. Artha also lists its various relatives like Synonyms, Antonyms, Attributes, Derivatives, Entails, Causes, Kinds, is Kind of, Member of, Members, Substance of, Substances, Parts, is Part of, Topics, Topical Terms, Region, Regional Terms, Usages, Usage Terms and Similar terms.
Artha’s many capabilities comes from the incredible WordNet database upon which Artha is based on. WordNet superficially resembles a thesaurus, in that it groups words together based on their meanings. However, there are some important distinctions. First, WordNet interlinks not just word forms but specific senses of words. As a result, words that are found in close proximity to one another in the network are semantically linked. Second, WordNet labels the semantic relations among words, whereas the groupings of words in a thesaurus does not follow any explicit pattern other than meaning similarity.
One of the most important feature of Artha is the quick hotkey lookup feature. When you are reading an article in the browser or a document, or composing a mail on a mail client, you can select a term in it and press the pre-set hot key combination assigned to Artha. This will pop open the program with the definitions of the selected term. Artha can also show passive notifications in balloon tips instead of the application's window popping up, so that you can continue what you were doing, uninterrupted.
Artha supports regular expressions search. When a word is vaguely known or the user is unclear of its spelling, the user can use wildcards (*), jokers (?), range, limits and other advanced search parameters. Artha can also correct misspelled queries and offer near-match suggestions.
Another distinctive feature of Artha, as already said, is Relatives. For every word you look up, Artha shows several relatives which includes:
- Synonyms: Words that infer the same meaning
- Antonyms: Words that expresses the opposite meaning
- Derivatives: Terms that have the same root form and are semantically related to the given word. E.g. clear and clarity.
- Pertainyms: Related nouns or verbs. E.g. culinary's pertainyms are cuisine, cooking, cookery.
- Attributes: Noun for which adjectives express values. E.g. weight has attributes heavy and light.
- Similar Terms: Terms which are not exactly synonyms but they convey a similar meaning. E.g. Similar terms to clear are permit, remove, disappear.
- Domain Terms: Terms that are specific to a subject. E.g.. contrast, underdeveloped, overexposed, etc. are domain terms of the topic photography.
- Causes: Terms that denote what a verb causes in doing it. E.g. kill causes to die.
- Hypernyms: Generic terms used to designate a whole class of specific instances. E.g. water is a kind of liquid. Hence liquid is a hypernym of water.
- Hyponyms: The opposite of hypernym. E.g. water is a hyponym of liquid.
Artha is one of the most comprehensive offline dictionary you can get hold of, and that too, free of charge.