"I began this project after I looked one day for a free dictionary of word origins online and found that there was none. You could subscribe to the Oxford English Dictionary for $550 a year. [As of January 2004, OED Online is now available by annual subscription to individuals for $295 a year, and has recently introduced monthly subscriptions for $29.95.] There were free dictionaries with definitions, some lists of slang words and their sources, and some sites that listed a few dozen of the strangest etymologies of English words. But there was no comprehensive public list of the words we use every day -- words like the and day -- that told what they used to be before we got them.  
For some reason no university has seen fit to shackle its graduate students to the cyber-mill, grinding out an online etymology dictionary. So I decided to do it for them. I also did this to increase my understanding of the language, and its ancestors and relatives. As a writer and editor with an amateur's passion for linguistics, I took this as a joy ride more than drudgery. And I know so much more useless trivia than I did when I started (applaud is related to explode; three people can have a dialogue; and if anyone calls you feisty, slug him).  
Etymologies are not definitions; they're explanations of what our words meant 600 or 2,000 years ago. Think of it like looking at pictures of your friends' parents when they were your age. People will continue to use words as they will, finding new or wider meanings for old words and coining new ones to fit new situations. In fact, this list is a testimony to that process.  
The same word usually exists in English in many forms -- cross, for example, is a noun, a verb (both transitive and intransitive), an adjective, and an adverb -- and I haven't broken down the history of each form. Words are generally listed in the form in which they are first attested in English."
phlap: Great! thanks.
Superb, lola...
...gave it a 10!
Darwish: link (n.) c.1440, "one of a series of rings or loops which form a chain," probably from O.N. *hlenkr (cf. O.Sw. lænker "chain, link," Norw. lenke, Dan. lænke), from P.Gmc. *khlankijaz (cf. Ger. lenken "to bend, turn, lead," gelenk "articulation, joint, link," O.E. hlencan (pl.) "armor"), from PIE base *qleng- "to bend." The verb (1387) is believed to be from the noun, though it is attested earlier. Missing link between man and apes dates to 1880.  
filter (n.) c.1400, from M.L. filtrum "felt," which was used to strain impurities from liquid, from W.Gmc. *filtiz (see felt). Of cigarettes, from 1908. The verb is from 1576; the fig. sense is from 1830.  
lorddimwit: It's an old link, but I'm still bumping it up. If you ever seriously want to use words for the advancement of good (or evil), you need an etymological dictionary. The OED is (obviously) the best, but this one has always served me well.  
lagbnaft: Very nice Lola, I just tried to post this myself.