(Le) Noyer as a noun means walnut (the tree, or its wood), while (la) noix is used for walnut the nut. Larousse also mentions noix de cajou (cashew) and noix de coco (coconut), and has this comment about the English word nut:
terme générique pour les amandes, noisettes, noix etc.(generic term for almonds, hazelnuts, walnuts, etc.), which made me wonder, "Is there no generic word for nut in French?"
Given the usage of noix as a component of other nut names, I had some suspicion that it might fill the bill. A native French speaker, a retired French professor (Merci, Mme J.), confirmed that noix could be so used, despite / beyond its primary meaning of walnut.
I also looked up se noyer, which means to drown (intransitive), potentially including the reflexive use of intentionally committing suicide that way. Just as in English, without adequate context (e.g., additional verbiage), it would not necessarily be clear which usage is meant.
Soon thereafter, I came across the word noyé (a drowned person) in Port Coton, a French pop song by Zaz, which I mentioned in this other blog entry. You never know where you'll come across new vocabulary words again, so grab as many as you can hang on to!