EOW is an online tool which attempts to translate single words from Modern English to Old English, and vice-versa. It currently recognizes 5070 Old English words and 5829 Modern English ones.

Old English, also called Anglo-Saxon, is the language spoken by the English inhabitants of Britain from about 500 to 1100 A.D. Though it's the ancestor of our modern English speech, it's different enough that translation is quite an effort. If you'd like to know more about Old English, you might try any of these links.

Note that Old English is not the language of Chaucer (who spoke Middle English), or Shakespeare (who spoke an early form of Modern English).

DISCLAIMER: This project was done purely for fun by a dedicated amateur; I make no promises about its results.