Why is the ninth month called September?
early 15c., "ligament in the neck," from Latin cervix "the neck, nape of the neck," from PIE *kerw-o-, from root *ker- (see horn (n.)). Applied to various neck-like structures of the body, especially that of the uterus (by 1702), where it is shortened from medical Latin cervix uteri (17c.). Sometimes in medical writing 18c.-19c. cervix of the uterus to distinguish it from the neck sense.
cervix cer·vix (sûr'vĭks)
n. pl. cer·vix·es or cer·vi·ces (sûr'vĭ-sēz', sər-vī'sēz)
A neck-shaped anatomical structure, such as the narrow outer end of the uterus.