Encyclopedia of Life Sciences. Nature Publishing Group.
Available online. Launched in 2001, updated monthly.
Oxford Reference.
Online searchable fulltext of over 175 dictionaries, encyclopedias, and other reference books on a variety of subjects. List of books included.
Oxford English Dictionary.
Available online. Published 1993-1997, updated quarterly. Current and historical meanings of words.
Origin of the Species includes many terms not in use today, either because word spelling has changed (teazel or teazle is now spelled teasel) or because the terms are no longer commonly used (most of us are more familiar with a microwave than with a turnspit dog).
Oxford Reference is a good place to look for archaic words and spellings. It includes the Concise Oxford English Dictionary and other dictionaries and guides, but not the famous Oxford English Dictionary (OED).
