What does Mĕnaeus mean in Latin?

Mĕnaeus, a adjective, means “adj., of”.

adjective

Mĕnaeus

Mĕnaeus, a, um,

I. adj., of or belonging to the city of Menæ, in Sicily: comitata Menaeis (viris), Sil. 14, 266.

mēnaeus, i, m., = μηναῖος,

I. monthly; subst. (sc. circulus), a monthly circle (al. manacus), Vitr. 9, 8.