Suffixing words with -ness, -ish, -like, and others

Question

Background

In a huge amount of the books I read the author has coined a little term to help them describe something, or an onomatopoeia. Like:

• Kindish (adding -ish to the end of a existing word)

• Elfness (adding -ness to the end of an existing (race name) word)

• Hobbit-like (very common. Adding a dash and then 'like')

• There are probably others which I can't think of right now.

I see this all the time in the texts I look at. I obviously still know what they mean, and it has quite a good effect in the writing. I like it, to be honest.

Question

To what extent can this be done before you fail to be understood?

When is an appropriate time to use this technique?

I'm planning on coining a bit of a term: 'tonitrious'. I want to make a madman use this while enjoying the lightning and thunder way too much. I just turned tonitrus an adjective. I think having this crazy word that originated from Latin gives a weird, lunatic(ish/-like, haha) maddening feeling.

I seriously doubt that my readers, considering my target audience is 13-16 will have heard of 'tonitrus'. It's pretty funny actually, because I'm in that age range. However, I know for a fact that other people won't know it. Do you think I'll get away with it?

"Oh, deafening sky! Tonitrious night!"

That's the kind of way I might use it.

Answer 1

The extent to which you can do this varies depending on your audience, but generally, I wouldn't do it with a thoroughly unknown word. Tonitrus is an excellent example. Great word, means what you need it to mean, but in itself it's already so rare that your readers will have to look it up. If you are then coining an adjective on top of it, you're going to lose people entirely, because you can't look that one up. So yes, create new words, but base them on familiar stems.

Keeping that in mind, I wouldn't overdo it in any one story, but go ahead and use it when you think it works. As long as your base word is understandable, make your new adjectives where necessary. Just check with your beta readers to make sure you're not too heavy-handed.