Lewis & Short

Solonĭum, ii, n., a district near Lanuvium, on the Via Ostiensis, Cic. Div. 1, 36, 79; 2, 31, 66; id. Att. 2, 3, 3.
Called also Solonius ager, Liv. 8, 12; Fest. s. v. pomonal, p. 250, b. Müll.