WordWeb!

The free Dictionary.com app delivers content from Dictionary.com and Thesaurus.com, including nearly a million words and definitions and 90,000 synonyms and antonyms. No internet required!

Lingoes is an easy and intuitive dictionary and text translation software. It offers lookup dictionaries, full text translation, capture word on screen, translate selected text and pronunciation of words.Lingoes sits in the system tray and becomes ones pop-up dictionary and thesaurus, as well as ones text and URL translator both from and to English, French, German, Spanish, Italian, Russian, Chinese, Japanese, Korean, Swedish, Thai, Turkish, Vietnamese, Greek, Polish, Arabic, Hebrew and more than 80 other languages. Included in its bag of pop-up tricks are conversion tools, calculators, abbreviations, word origins, slang, idioms and much more. Entire dictionaries may be freely downloaded; and realtime look-ups at several well-known online dictionaries and translators is built right in. »

Artha is a handy thesaurus based on WordNet with distinct features like global hotkey look-up, passive desktop notifications, regular expression based search, etc.. Artha may be used as a free open-source replacement to the proprietary WordWeb Pro.

Dictionary and offline Wikipedia reader.

WordNet® is a large lexical database of English. Nouns, verbs, adjectives and adverbs are grouped into sets of cognitive synonyms (synsets), each expressing a distinct concept. Synsets are interlinked by means of conceptual-semantic and lexical relations. The resulting network of meaningfully related words and concepts can be navigated with the browser. WordNet is also freely and publicly available for download. WordNet's structure makes it a useful tool for computational linguistics and natural language processing. »

This program can look for the definition or translation of a word in existing databases over the Internet or over local databases. It is extremely simple to use.

Power Thesaurus is a fast, comprehensive and easy-to-follow online thesaurus for writers, journalists, students and teachers

TheSage is a powerful language reference system that couples a professional dictionary of the English language with multifaceted and extensive thesaurus

Access all your favorite dictionaries and other lookup services in one place.

TemaTres is an open source vocabulary server, web application to manage and exploit vocabularies, thesauri, taxonomies and formal representations of knowledge.

Strap a jetpack to your Korean writing & reading level with software designed for non-native Korean users

The Top Words Like website is a great resource for finding synonyms for any given word. More information such as examples and definitions are displayed.

An online dictionary for learning the meaning of a word along with the meaning of the words within its definition.