Reference Directory
RefSeek's guide to the 30 best online dictionaries, thesauri, and definition aggregators. Listings are judged by authority, coverage, usability, and utility.
Directory and search engine for acronyms and abbreviations.
abbreviations.com - Acronyms
Provides definitions for more than five million acronyms and abbreivations.
acronymfinder.com - Acronyms
Dictionary and encyclopedia including 25,000 entries and 6,000 images.
computerlanguage.com - Computers
Aggregates definitions from multiple respected dictionaries.
definitions.net - Aggregator - Also see: Synonyms.net
Includes definitions from American Heritage, Random House, and Merriam-Webster.
dictionary.com - Aggregator - Also see: Thesaurus.com
Concise, easy-to-understand definitions from The People's Law Dictionary.
dictionary.law.com - Legal
English and Spanish dictionary and thesaurus from Oxford University Press.
lexico.com - Dictionary
Source of mathematical definitions and concept explanations.
mathworld.wolfram.com - Math
Based on the print version of Merriam-Webster's Collegiate Dictionary.
merriam-webster.com - Dictionary
6,000 full-color illustrations; 20,000 terms with contextual definitions.
visualdictionaryonline.com - Dictionary
Definitions for thousands of terms in the field of technology and communication.
netlingo.com - Technology
Explanations of what our words meant and how they sounded hundreds of years ago.
etymonline.com
Aggregator of medical definitions for 10,000+ medical concepts with images and pronunciations.
openmd.com - Also see: Medical Abbreviations
General and subject dictionaries for financial, legal, and medical terms.
thefreedictionary.com
Over 17,000 entries. Find synonyms, antonyms, and definitions.
thesaurus.com - Thesaurus
Dictionary of contemporary American slang. Not appropriate for children.
urbandictionary.com - Slang
Displays a unique visualization of connections between words.
visualthesaurus.com - Thesaurus
Outstanding dictionary and engaging vocabulary teaching tool.
vocabulary.com - Dictionary
Easy-to-understand definitions for thousands of technology terms and acronyms.
webopedia.com - Technology
Multilingual dictionary and thesaurus written and edited by the public.
en.wiktionary.org - Dictionary
Builds dynamic trees that are filled with synonyms, antonyms, syntactical associations.
wordflex.com - iPad Only
Dictionaries, word tools, and an amazing illustrated dictionary for children.
wordsmyth.net - Also see: Illustrated Dictionary for Kids
Definitions, thesaurus entries, spelling, pronunciation, and etymology results.
yourdictionary.com - Aggregator
Word Tools
Find answers to crossword puzzles, anagrams and cryptograms.
oneacross.com - Crosswords
Explore and compare the popularity of words over time and geography based on Google search data.
trends.google.com
Remarkable, robust anagram lookup service from Wordsmith.
wordsmith.org - Anagrams
Excellent rhyming dictionary with phonetic word search, thesaurus, and near rhymes.
rhymedesk.com
