di·a·phragm 
/ˈdajəˌfræm/ noun
plural di·a·phragms /ˈdajəˌfræm/ noun [count] 1 medical : a large flat muscle that separates the lungs from the stomach area and that is used in breathing — see picture at human 2 technical : a device that controls the amount of light passing through the lens of a camera 3 : a device shaped like a cup that is placed in the vagina to prevent pregnancy —called also (Brit) cap 4 technical : a thin disk that is used in microphones, telephones, speakers, etc., to help reproduce sound or make sounds louder
