os uterin.

1638 A. Read Man. Anat. Body of Man (new ed.) xxvi. 241 It [sc. the matrix] hath two parts, os uteri, the mouth of the matrix, and fundus the bottome.

1724 Philos. Trans. 1722–3 (Royal Soc.) 32 429 He shews, that in reality it is a Calyx, or natural Aperture, which enlarges itself for that purpose by Degrees, and after Exclusion closes again, as the Os Uteri afterwards.

1754–64 W. Smellie Treat. Midwifery I. 193 If the os uteri remains close shut.

1859 Todd's Cycl. Anat. & Physiol. V. 638/2 Outwardly, this scaly epithelium is continuous with that of the vagina, but towards the os uteri it terminates at the margin of either lip.

1913 Cunningham's Text-bk. Anat. (ed. 4) 1316 In the vaginal portion of the cervix there is an opening—the orificium externum uteri (O.T. external os uteri).

1993 N.Y. Rev. Bks. 18 Nov. 52/1 Some of the contraceptive methods that Greek doctors of the Roman period recommended, particularly the use of spermicidal substances and of other substances that blocked the os uteri, are at times likely to have worked.