Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
fĭdĕjussĭo, ōnis, f. [fidejubeo], jurid. t. t., a giving or being surety; suretyship, bail: servus fidejussionis nomine obligari non potest, Dig. 46, 1, 20; ib. 10, 2.