[This answer](https://linguistics.stackexchange.com/a/6366/3571) got me thinking about words that exist in many languages but don't exist in a few. It states that there was no word for *and* in PIE. I had [previously read](https://en.wikipedia.org/wiki/Yes_and_no) that **Some languages do not answer yes–no questions with single words meaning 'yes' or 'no'.** Instead they **typically employ echo answers**. E.g. *Is it hot?* might be answered with *It is [hot]* or *It isn't [hot]* instead of *yes* or *no*.

How can I find out which words are ~~missing~~ unrepresented in a language, where the same concept is commonly represented in other languages as a single word?