Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
tăbānus, i, m., a gad-fly, horse-fly, oxfly, breese; called also asilus, Varr. R. R. 2, 5, 14; Plin. 11, 28, 34, § 100; 11, 33, 38, § 113; 30, 11, 30, § 101.