diaphragm Look up diaphragm at Dictionary.com
late 14c., from L.L. diaphragma, from Gk. diaphragma (gen. diaphragmatos) "partition, barrier," from diaphrassein "to barricade," from dia- "across" + phrassein "to fence or hedge in." The native word is midriff. Meaning "contraceptive cap" is from 1933.