Etymology

Altaic Etymology
Online database version of the Altaic Etymological Dictionary by S. Starostin, A. Dybo and O. Mudrak.
http://starling.rinet.ru/cgi-bin/startq.cgi?flags=eygtnnl&root=config&basename=%5Cdata%5Calt%5Caltet

American Dialect Society
A scholarly association dedicated to the study of the English language in North America.
http://www.americandialect.org/

Businessballs.com - Etymology of Clichés, Expressions and Words Etymology
English language terms and expressions.
http://www.businessballs.com/clichesorigins.htm

A Comparative Dictionary of Indo-Aryan Languages
Online version of the indexes of R.L. Turner's 1962-1985 dictionary from the Digital Dictionaries of South Asia.
http://dsal.uchicago.edu/dictionaries/soas/

Dave Wilton's Etymology Page
Devoted to etymology of common words and slang phrases.
http://www.wordorigins.org/

English Language Roots: The Meanings of Word Prefixes, Suffixes and Syllables
Reference chart for Greek, Latin, and other roots of the English language. Understanding such roots can help guessing the meaning of words and creating neologisms or brand names.
http://www.prefixsuffix.com

Etymologic
The brain-twisting etymology game.
http://www.etymologic.com/

Etymologically Speaking
A list of some curious word origins.
http://www.westegg.com/etymology/

Etymology
Word origins and links.
http://members.tripod.com/~itsmagic/ETYMOLGY.HTML

European Sayings & Idiomatic Expressions
Dedicated to gathering sayings and idioms and their translation/explanation from all over Europe. User contributions welcome.
http://sayings.jacomac.de/

Exploring English Words
Exploring English words that are derived from Latin and Greek sources with etymologies and vocabulary activities.
http://www.wordexplorations.info

Focusing on Words
An advanced Latin-Greek-English vocabulary source of etymologies with thematic units of roots, prefixes, and suffixes, and vocabulary quizzes.
http://www.wordfocus.com/

languagehat.com
Erudite blog on word origins and definitions, with dozens of links to dictionaries, commentaries, linguistic reference sites, and personal favorites of the author.
http://www.languagehat.com/

MooT
The game of grammar, semantics, and etymology. Play online the game that investigates the history and meaning of English words.
http://www.mootgame.com/

Nautical Expressions in the Vernacular
Myriad expressions in everyday English have nautical origins. This web page lists expressions and definitions mentioned by listswains, members of the Patrick O'Brian Mailing List, also known as the Gunroom.
http://www.io.com/gibbonsb/words.words.words.html

New Words In English
Neologisms and novel uses of words in English collected by members of the class Linguistics/English 215, Words in English: Structure, History and Use, taught by Suzanne Kemmer at Rice University.
http://www.owlnet.rice.edu/~ling215/NewWords/index.html

Online Etymology Dictionary
History and evolution of more than 30,000 words, including slang and technical terms.
http://www.etymonline.com/

Oxford English Dictionary
Presents a word a day complete with pronunciation, spellings, etymology, quotations and date chart.
http://oed.com/cgi/display/wotd

Pandora's Word Box
Relates medical terminology to the humanities, offering a weekly overview with references to classical etymology.
http://pandorawordbox.com/

The Phrase Finder
The meanings and origins of thousands of English phrases and sayings. Also includes a discussion forum to ask a panel questions on the meaning and origin of phrases.
http://www.phrases.org.uk/

Richard Lederer's Verbivore
Linguistic fun from, Richard Lederer, the best-selling author of The Word Circus and the new Sleeping Dogs Don't Lay, a helpful guide for grappling with vexing grammar questions.
http://www.verbivore.com/

Roots of English
An etymological dictionary you can download by Prof. Eugene Cotter, Seton Hall University.
http://ablemedia.com/ctcweb/showcase/roots.html

Sayings and Everyday Expressions
Your online source for the sayings and expressions you use everyday. Search for their meaning, history and origin, find sayings, expressions, phrases, quotations, cliches, unusual words, and wordplay.
http://users.tinyonline.co.uk/gswithenbank/sayindex.htm

Taiwan Teacher
A new word or phrase posted every week giving you the meaning, origin and an example of the usage of the word or phrase.
http://www.geocities.com/athens/delphi/1979/trivia.html

Take Our Word for It
Weekly etymology magazine.
http://www.takeourword.com/

What's The Meaning of This?
The origins of quirky English words and phrases like "In like Flynn" and "blackmail."
http://www.rootsweb.ancestry.com/~genepool/meanings.htm

Word and Phrase Origins
Directory. Part of the Internet Public Library. Describes books and web sites that might be helpful. Offers a hint on how to use an ordinary search engine when looking for etymology.
http://www.ipl.org/div/pf/entry/48468

The Word Detective
Words and language in a humorous vein. The online version of The Word Detective, a newspaper column answering readers' questions about words and language. Written by Evan Morris.
http://www.word-detective.com/

Word Origins
This regularly updated page, provided by The Writer's Place, focuses on a word and its spelling, pronunciation, and derivation.
http://www.thewritersplace.com/writestuff/origins.htm

Word Origins and Meanings of Economic Terms
Click on a word and go right to a brief discussion of its origin.
http://www.louisville.edu/~bmhawo01/econpage/meanings.html

Word Quests for Word Seekers
Searchable dictionary of word origins, organized in cross-referenced thematic lists by Latin and/or Greek roots. English entries are also defined.
http://www.wordquests.info

Word Sources
Includes a searchable database of Latin and Greek roots and affixes, a free newsletter, and links to other sites.
http://www.wordsources.info/

Word Spy
Collection of recently coined words, existing words that have enjoyed a recent Renaissance, and older words that are now being used in new ways.
http://www.wordspy.com/

Words with Heathen Origins in the Scriptures
An etymological study of numerous words used in churches and Scriptures that have their origin in pagan religions.
http://www.innvista.com/culture/religion/bible/compare/heathen.htm

World Wide Words
Michael Quinion writes about International English from a British viewpoint. Hundreds of pages on the history, origins, evolution and idiosyncrasies of English, with features on new words and words in the news.
http://www.worldwidewords.org/