Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ob-nūbĭlo, āvi, ātum, 1, v. a., to cover with clouds or fog; to overcloud, darken, obscure (post-class.): vultūs serenitatem, Gell. 1, 2, 5: haec omnia vitium, to obscure, Amm. 28, 4, 2: odore sulfuris obnubilatus, beclouded, stupefied, senseless, App. M. 9, p. 228, 22; so, animam, id. ib. 8, p. 204, 38.