Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Sēplā̆sĭa (ă, Aus. Epigr 123; ā, Marcell. Medic. 66), ae, f. (Sēplā̆sĭa, ōrum, n., Varr. ap. Non. 226, 16), a street in Capua, where unguents were sold: Seplasia platea Capuae, in quā unguentarii negotiari sunt soliti, Ascon. Cic. Pis. 11, 24, p. 10 Orell.; so Varr. ap. Non. 226, 18; Cic. Pis. 11, 24; id. Agr. 2, 34, 94; id. Sest. 8, 19; Plin. 16, 10, 18, § 40; 33, 13, 57, § 164: fraus Seplasiae, i. e. ointments adulterated in the Seplasia, id. 34, 11, 25, § 108; Val. Max. 9, 1, 1 ext.
In plur., Pompon. ap. Non. 226, 20.
Hence,