ocean09 said:
it means "nervous," but I'm not sure what language it is.
It's German (Deutsch), but 'nervous' is usually 'nervös', and anxious would be 'ängstlich, bange, unruhig', and worrisome is 'beunruhigend, besorgniserregend'.
It would help to have the context. Also, if one googles "nervenmäßig" one will find many German websites, but the context varies.
I was leaning toward 'anesthetic' or 'tranquilizing' as the definition.
Further elaboration - the German adjectival suffix '-mäßig' means '-like', so it would appear that 'nervenmäßig' would mean 'nervous', but I don't know how common this usage is as compared to 'nervös', or other synonyms.
A friend for whom German is a third language has indicated that 'nervenmäßig' or perhaps being used as a noun 'Nervenmäßig' could mean simply 'nerves', as in 'one is being treated for nerves', which is a reference to being nervous/anxious/worried rather than a reference to the physiological structure. In other words, it's German vernacular. This is a guess on my part without knowing the context.