Want to use that fancy title but not sure it's period? Want to talk about something but not sure the right words?
I offer to you:
etymonline.com/index.php
This is an etymology (read: history of words) site that I have used for years, including in the pursuit of my linguistics degree. The creator of the site admits that he is not a final authority, but he does reference some VERY viable sources - just makes it easier than finding all those varied books myself. It's a great resource if you're looking to build a structure or hierarchy (trade company, business, military organization) or even just if you want to know how the meaning of a word has changed over time. Many common-use words have a pretty detailed historical record and can be traced back to a similar time as when Travance is set.
Enjoy!