*endometriosis
endometrium = uterine mucous lining
-osis = in the wrong place aka -iasis,
definitions if you must:
A condition, usually resulting in pain and dysmenorrhea, that is characterized by the abnormal occurrence of functional endometrial tissue outside the uterus.
A condition, usually resulting in pain and dysmenorrhea, characterized by the abnormal presence of functional endometrial tissue outside the uterus, frequently as cysts containing altered blood.
The presence and growth of functioning endometrial tissue in places other than the uterus that often results in severe pain and infertility.