Online Etymology Dictionary

A very useful resource - Online Etymology Dictionary

"This is a map of the wheel-ruts of modern English. Etymologies are not definitions; they're explanations of what our words meant and how they sounded 600 or 2,000 years ago. The dates beside a word indicate the earliest year for which there is a surviving written record of that word (in English, unless otherwise indicated). This should be taken as approximate, especially before about 1700, since a word may have been used in conversation for hundreds of years before it turns up in a manuscript that has had the good fortune to survive the centuries".