I'm currently reading through the story "The Last Test," and--as is bound to happen now and then during a Lovecraft reading session--I came upon a word I did not recognize. My Nook informed me that there was no definition for this particular word, so I went online and tried again: "Testudinous..." Google thought I'd made a typo and suggested instead "testudineous," which means "tortoise-like" or "resembling a tortoise shell."
I reversed Google's unwanted correction and searched again. Very few hits. Hm. I moved on to the trusty ol' Ngram viewer (oh how I love that thing!) and searched for it there. Got a few hits, so on a whim I pulled open one of the earliest mentions. It was a reference book entry:
TESTUDINOUS, adj. [L. testudineus, from testudo, a tortoise.]
Resembling the shell of a tortoise.
Again, hm. The Latin spelling is a homophone for the suggested spelling Google gave me. Looks like we have two legitimate alternate spellings of a word, neither of which anyone uses anymore. I Ngram'ed them against one another and found that the -eous spelling was slightly more frequently used in print than Lovecraft's version, reaching an undisputed peak of usage in the early 1890s.
So, satisfied with the definition and its bearing on the story (the ascetic doctor's unique and quirky assistant, Surama, "indulged in many a deep, testudinous chuckle," or deep, slow-paced and deliberate chuckles), I turned back to this reference book I found through the Ngram viewer. Wow. What a title! Here's the title page, direct from the scan of the original 1832 printing:
The best news is that you can read the whole thing through Google Books by following this link. I guarantee you'll find some intriguing words in this book. It's easy to get hooked once you start digging. I swear to you, Lovecraft must have had access to a copy of this book because just about every page yields something I know I've read in his many stories.
I'm happy I found this valuable compendium of lexicographical knowledge. Have a look yourself. Expanding your vocabulary is a great way to learn more about the world around you and about yourself. It also allows you to more accurately express yourself. If that's not enough of a bonus, building your vocabulary can only have positive effects on your professional life. Ever heard of anyone getting canned because they have stellar communication skills?
If you think this book is surely antiquated and no longer relevant since it was published in the 19th Century, then I have news for you. It's been reprinted several times over the last 180 years. The 2010 paperback version, at 238 pages, is currently available on Amazon for the low, low price of $19.99! What are you waiting for? Grab some new words today!