Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† oecus, i, m., = οἶκος, a room in a house; a hall, saloon (only in Vitr. and Plin.): oeci magni, in quibus matresfamiliarum cum lanificis habent sessiones, Vitr. 6, 10; Plin. 36, 25, 60, § 184; cf. Becker’s Gallus, 2, p. 189 (2d ed.).