That's so weird. South Slavic languages have a word for thirsty and quick google search informed me that other Slavic languages have it as well. Unless I am mistaken, Russian is the only Slavic language with not word for "thirsty". That is so bizarre to me. Russians were never thirsty, they had vodka. :D
There is a Russian word for thirsty: Жаждущий. But it fell out of use some time ago. The same applies to hungry and sleepy. You have to figure out from the context what is really meant. Do they want something or are they just saying that they are thirsty, hungry or sleepy?
Very peculiar in the Russian language. Thirsty = want to drink (хотеть пить) Hungry = want to eat (хотеть есть) Sleepy = want to sleep (хотеть спать) Especially the last one is confusing. One can be sleepy, but still doesn't want to lie down and sleep. (And maybe one can be hungry but doesn't want to eat while on a diet.)
If somebody asks you "Does she drink?" you could answer "No." or "She does not drink." either would be sufficient. If you say "No, she does not drink.", you're using two negatives "no" and "not" which would be a double negative in my book. Of course "No, she does not drink." is considered correct classroom English, but it's still a double negative.
It has two negatives (no and not) negating the same thing (whether she wants to drink). In the same sentence mind you. One of the negative is superfluous. That's a double negative to me. And yet perfect classroom English. I present it as evidence of the capricious nature of the English grammarian.
I just pointed out that the definition you use is extremely unconventional. It does not matter how many things you negate—grammarians who seriously say otherwise probably are not worth their salt. . The thing that matters is whether there are multiple negations within the same structure. Some languages use it or even require consistent negation (e.g. Russian), some avoid it.
At least, a definition with a clause is a definition that makes some sort of sense. A sentence, on the other hand, is a loosely defined concept even in elementary school grammar, positively inapt when it comes to the analysis of negation structure in languages.