Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
circĭus (cercĭus, Cato ap. Gell. 2, 22, 28 sq.), ii, m. [perh. from circus, on account of its circular motion, but said to be a Gallic word], a violent wind blowing in Gallia Narbonensis; to the Romans, a west-northwest wind, Plin. 2, 47, 46, § 121; Sen. Q. N. 5, 17, 5, Vitr. 1, 6, 10; Suet. Claud. 17; Favorin. ap. Gell. 2, 22, 20 sq.