Double-Tongued Word Wrester Dictionary

The Double-Tongued Word Wrester Dictionary, created and maintained by an American lexicographer for Oxford University Press:

records undocumented or under-documented words from the fringes of English. It focuses upon slang, jargon, and other niche categories which include new, foreign, hybrid, archaic, obsolete, and rare words. Special attention is paid to the lending and borrowing of words between the various Englishes and other languages, even where a word is not a fully naturalized citizen in its new language.

(via Lifehacker)