Greek Grammar

ending with the great omega omega (ω) in neuter [nouns]. Of these, the genitive and dative are in the great omega, and the accusative is in the great omega. Clearly it ends in -n after the vowel of the nominative.
The Menelaōs. Menelaō. Menelaō. Menelaōn. ō Menelaōs. Dual: tō Menelaō. toin Menelaōn. ō Menelaō. Plural: hoi Menelaō. tōn Menelaōn. tois Menelaōs. tous Menelaōs. ō Menelaō.
The halōs threshing floor. tēs halō. tēi halō. tēn halōn. ō halōs. Dual: ta halō. tain halōn. ō halō. Plural: hai halō. tōn halōn. tais halōs. tas halōs. ō halō.
The eugeōn fertile land. tou eugeō. tō eugeō. to eugeōn. ō eugeōn. Dual: tō eugeō. toin eugeōn. ō eugeō. Plural: ta eugeō. tōn eugeōn. tois eugeōs. ta eugeō. ō eugeō.

Fourth Declension.

The fourth declension of nouns is also in the three genders, and it is isosyllabic: clearly all those ending in -os with the small omicron omicron (ο), whether masculine or feminine, and those in -on ending in neuter, except for comparatives. Of all of these, the genitive is in -ou, the dative in -ō, and the accusative ends in -n after the vowel of the nominative.