The gens Lemonia was a very ancient but obscure family at Rome. Hardly any members of this gens are known, and the name might be entirely forgotten, were it not for the fact that the Lemonii gave their name to one of the 17 Servian rustic tribes, since around 570 BC. In the middle of the sixth century BC they may have been major landholders in the region later known as the Pagus Lemonius - which was established along the via Latina - , but none of the Lemonii are known to have held any magistracies over the history of the Republic. A few Lemonii are known from inscriptions; a family of this name lived in Venetia and Histria. After their conquest Bononia and Dyrrachium were registered to the Pagus Lemonius.
According to an orientation, the family date back to the time of the first legendary Roman king, Romulus, among the 100 originary families. In any case, the Lemonii were already present in the middle of the sixth century BC, as for the establishment of the Pagus Lemonius.
Maybe the name Lemonius came from the greek word λειμον (lawn); in the zone of the Pagus Lemonius there was a grass called Leimonium. According to another theory, Lemonius derived from the presence in the Pagus of a flower belonging to the species of the Anemoni, the Limonium.