SOLVED. Adult Fantasy/ Horror about ancient languages that force one to do what is said. Proper language can be determined by asking questions including "Dog person or Cat Person". Possible Spoilers. [s]

[Rd]

I read this around 2010. It involves a linguist (?) who comes in contact with a group that has discovered a series of ancient languages that in both written and spoken form can force a person to do what is requested. At some point a written note is posted in the hospital of a remote village that causes the residents to kill one another. In order to determine which of the languages a person is vulnerable to, a series of questions are asked, including "are you a dog person or cat person." Thanks!

[Rd]

This was a hardcover. I really don't recall anything about the cover. Apologies there isn't much to work with.

[Rd]

I was able to backtrack this and discovered that the book was Lexicon by Max Barry!

[Kris]

Glad you found your book, Rd. Here's the link - Lexicon by Max Barry.