Ovarian mass; Adnexal mass
There are many causes for growths on the ovary. Your age and medical history are important in evaluating an ovarian growth.
Before menopause, the ovary forms a fluid-filled sac (ovarian cyst) every month as a normal part of the process of releasing an egg. There are other reasons why the ovary can form a cyst; most of these are not worrisome. If a cyst is large (over 5 centimeters), or doesn't go away after a few months, then you may need to have it further evaluated or removed.
Regardless of your age, have your doctor look at any ovarian growths that are complex or solid.
See also: Ovarian cysts