Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Aegĭum, or Aegĭon, ii, n., a town in Achaia, one of the twelve Achœan cities, situated on the river Selinus, now Vostitza, Mel. 2, 5, 10; Plin. 4, 5, 6, § 13; Lucr. 6, 585; Liv. 38, 30.
Hence,