Noun | 1. | ![]() conjunctiva - a transparent lubricating mucous membrane that covers the eyeball and the under surface of the eyelid tissue layer, membrane - a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants endometrium - (pregnancy) the mucous membrane that lines the uterus; thickens under hormonal control and (if pregnancy does not occur) is shed in menstruation; if pregnancy occurs it is shed along with the placenta at parturition maidenhead, virginal membrane, hymen - a fold of tissue that partly covers the entrance to the vagina of a virgin |