What does the term 'Nervosa' mean?

Obviously, I know it is a term used in both the names of medical/psychological conditions ( Bulemia Nervosa, Anorexia Nervosa, and the gland, Pars Nervosa ) along with in the Latin names of some plants ( Mahonia Nervosa, Pouteria Campechiana Nervosa ). But what exactly does the root word 'Nervosa' really mean? I believe the root is Latin, but I cannot find the meaning anywhere. Any help?