conjunctiva - a transparent membrane covering the eyeball and under surface of the eyelid

tissue layer, membrane - a pliable sheet of tissue that covers or lines or connects organs or cells of animals

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