General purpose: * [Online Etymology Dictionary][1] * [Google Books][2], set date range and sort by date* * [Google Ngram Viewer][3] * Bill Mullins has a giant list of [Full Text Databases][4] * [Internet Archive][19] * [Project Gutenberg][20] * [HathiTrust Digital Library][21] Newspapers: * USA: [Chronicling America][5] (1836-1922) by the Library of Congress * Australia: [Trove][6] (-1954) by the National Library of Australia * New Zealand: [Papers Past][7] (1839-1945) by the Nation Library of New Zealand Particularly for computing terms: * [Google Groups][8] for Usenet archives (also good for slang) (1981 - present) * [DSpace@MIT][9] for the CSAIL archives (1959 - present) * IETF's [RFC][10] archive (1969 - present) * [PDP-10 software][11] archive (~1967 - ~1990), for old source code * [Tech Model Railroad Club dictionary][12], TMRC [1st & 2nd editions][13] (1959, 1960) * [The Jargon File][14] and its [archives][15] ([also here][16]) (1981 - 2003) * MIT's [The Tech][17] newspaper archives (1881 - present) * [Bitsavers][18]' Software and PDF Document Archive (misc. dates) \* Care must be taken with Google Books' metadata, especially when only a snippet is shown: occasionally the book was published later than the the year Google claims it was, and sometimes they accidentally include multiple books for each record. Therefore it's important to double check the date: scroll up to confirm the real date for "full view" books, and for preview/"snippet view" verify with another source (such as the [Internet Archive][19], [Project Gutenberg][20] or the [HathiTrust Digital Library][21]). [1]: http://etymonline.com/ [2]: http://books.google.com/ [3]: http://books.google.com/ngrams [4]: https://sites.google.com/site/fulltextdatabases/ [5]: http://chroniclingamerica.loc.gov/ [6]: http://trove.nla.gov.au/newspaper [7]: http://paperspast.natlib.govt.nz/ [8]: http://groups.google.com/ [9]: http://dspace.mit.edu/ [10]: http://www.ietf.org/rfc.html [11]: http://pdp-10.trailing-edge.com/cgi-bin/searchbyname [12]: http://tmrc.mit.edu/dictionary.html [13]: http://www.gricer.com/tmrc/tmrc-dictionary-intro.html [14]: http://www.catb.org/jargon/ [15]: http://jargon-file.org/archive/ [16]: http://www.catb.org/jargon/oldversions/ [17]: http://tech.mit.edu/browse.html [18]: http://www.bitsavers.org/ [19]: http://www.archive.org/details/texts [20]: http://www.gutenberg.org/ [21]: http://www.hathitrust.org/