Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
essentĭa, ae, f. [sum], the being or essence of a thing; transl. of the Gr. οὐσία: haec interpretatio (rhetorices) non minus dura est, quam illa Flavii essentia atque entia, Quint. 2, 14, 2; 3, 6, 23; 8, 3, 33: cupio, propitiis auribus tuis, essentiam dicere. Ciceronem auctorem hujus verbi habeo, Sen. Ep. 58, 6.