Lewis Short
ostĭum (noun N) : kindred with Sanscr. oshtha, labium; Slav. ūsta, the same; cf. os
* A door (class.; cf.: porta, janua, fores, valvae).
* Lit.: omnia istaec auscultavi ab ostio,Plaut. Merc. 2, 4, 9: observare,id. Mil. 2, 3, 81: rectum ostium, the front-door (cf. posticum), Plaut. Mil. 2, 3, 58 Brix ad loc.: aperire,to open,Ter. Heaut. 2, 3, 35: operire,to shut,id. Phorm. 5, 3, 33: obserare intus,to bolt,id. Eun. 4, 6, 25: obdere pessulum ostio,id. ib. 3, 5, 55: concrepuit ostium a Glycerio,id. And. 4, 1, 58: inscribat aliquis arse verse in ostio, Afran. ap. Fest. p. 18 Müll.: ostium limenque carceris,Cic. Tusc. 5, 5, 13: aperto ostio dormire,id. Rosc. Am. 23, 65: quaerere ab ostio,id. de Or. 2, 68, 276: exactio ostiorum,doortax,id. Fam. 3, 8, 5; v. 2. ostiarius, III.: sepulcri,Dig. 43, 23, 11.
* Transf., a mouth, an entrance of any kind: Acheruntis ostium in nostrost agro,Plaut. Trin. 2, 4, 124: aperto ex ostio Alti Acheruntis. Poët. ap. Cic. Tusc. 1, 16, 37: sacra Inferni ostia,Verg. G. 4, 467; id. A. 6, 109: ne in rimis areae grana oblitescant, et ostia aperiant muribus ac formicis,entrances,Varr. R. R. 1, 51, 1: portūs,Cic. Verr. 2, 4, 53, § 118: fluminis,mouth,id. Phil. 2, 11, 26; Liv. 24, 40; 44, 6; 44, 45; cf. Rhodani,Caes. B. C. 2, 1: Tiberinaque ad ostia venit,Ov. M. 15, 728; cf. Verg. A. 1, 13: Oceani,i. e. the Strait of Gibraltar,Cic. Imp. Pomp. 12, 33; Mel. 3, 9, 3.—Fig.: ego sum ostium ovium,Vulg. Johan. 10, 7.
Charlton T. Lewis, Charles Short, A Latin Dictionary