Is it ensure, insure, or assure?
late 14c., from Late Latin diaphragma, from Greek diaphragma "partition, barrier, muscle which divides the thorax from the abdomen," from diaphrassein "to barricade," from dia- "across" (see dia-) + phrassein "to fence or hedge in." The native word is midriff. Meaning "contraceptive cap" is from 1933.
diaphragm di·a·phragm (dī'ə-frām')
A musculomembranous partition separating the abdominal and thoracic cavities and functioning in respiration. Also called midriff.
A membranous part that divides or separates.
A contraceptive device consisting of a thin flexible disk, usually made of rubber, that is designed to cover the uterine cervix to prevent the entry of sperm during sexual intercourse.
A disk having a fixed or variable opening used to restrict the amount of light traversing a lens or optical system.
A dome-shaped structure made up of muscle and connective tissue that separates the abdominal cavity from the thorax and functions in respiration. By movement of the diaphragm, air is either drawn into the lungs or forced out of them.
Note: The term diaphragm can also refer to a small flexible cap, usually made of rubber, that fits over the cervix and is used for contraception.