Is turbid that rare a word?

I asked both my kids if they knew what it meant. They didn't. I asked them if they'd be bothered by it if it was in a book. Neither of them would be. My 9 year old said "I'd just ask a grown-up" and my 13 year old said "I'd just read on and work it out from context".

I think adults systematically underestimate children. People learn language by being exposed to it and children are better at this than adults so not using less common words in case children don't understand them strikes me as illogical and counterproductive.

I agree that ensuring the vocabulary fits the character's/narrator's voice and that it all works creatively is important, but if it works creatively and the only reason you're thinking of not including the word is fear that children won't understand it, then use it.

From my own experience as a child, the words that tripped me up while reading books weren't the rarer standard English words, but were US dialect words. They didn't stop me from reading on, they just provoked some hilarious mental images as I tried to figure them out from context. (Like how I thought "bangs" was some kind of hair clip.) If British kids can cope with US dialect words in books then surely kids from all over the English-speaking world can cope with a few unfamiliar words from standard English.