• The layer of tissue that lines the uterus.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• The lining of the uterus.
  Harvard Dictionary of Health Terms
  Harvard Medical Publishing, 2011
• The mucous membrane comprising the inner layer of the uterine wall; it consists of a simple columnar epithelium and a lamina propria that contains simple tubular uterine glands. The structure, thickness, and state of the endometrium undergo marked change with the menstrual cycle.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• The mucous membrane lining of the uterine cavity that is hormonally responsive during the menstrual cycle and PREGNANCY. The endometrium undergoes cyclic changes that characterize MENSTRUATION. After successful FERTILIZATION, it serves to sustain the developing embryo.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021
• Tissue lining the uterus, it is sloughed off during the woman's menstrual period, and afterward grows back and slowly gets thicker and thicker until the next period.
  CRISP Thesaurus
  National Institutes of Health, 2006