Where does “nerve” come from?

nerve (Middle English) comes from Medieval Latin nervus, from Latin nervus, from Proto-Indo-European (s)new-.

Ancestry of “nerve”, step by step

Step	Language	Word	Meaning
1	Medieval Latin	nervus	nerve; A sinew, tendon, nerve, muscle; A cord,...
2	Latin	nervus	A sinew, tendon, nerve, muscle; A cord, string or...
3	Proto-Indo-European	(s)new-	—