Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
fĭdĕjussor, ōris, m. [fidejubeo], jurid. t. t., one who gives security for any one, a bail, a surety under the most binding form known to the Roman law, Gai. Inst. 3, 115-127: De fidejussoribus, Just. Inst. 3, 20; Dig. 27, 7; 46, 1; Cod. Just. 5, 57; 8, 41; Ambros. de Tob. 12, 89; Vulg. Prov. 20, 16.