Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
jactantĭa, ae, f. [jacto], a boasting, bragging; display, ostentation (post-Aug.): sui, Tac. A. 2, 46: militaris, id. Agr. 25: frivola in parvis, Quint. 1, 6, 20; 9, 2, 74: partim jactantia ingenii, ut res cito accepisse videantur, id. 12, 8, 3: privatae studere, Plin. Ep. 1, 8, 13; id. Pan. 38, 4.