Cachinnatous

I was reading David Brin's The Uplift War. This is the first science fiction book that I've read in some time, and it's terrific so far. The aliens and humans in this book have a separate language which is interesting to read (the book provides a glossary). Of course, there are English words that I have to look up, and one of them was cachinnatous. The online dictionary I use didn't have this word, but they had a similar word called cachinnatory, which is an adjective for "accompanied by immoderate laughter". That seemed to fit the sentence (the word was used in "a gaggle of cachinnatous humans"). Humans laughing a little too loudly perhaps? I think so.