Lewis & Short

2. ēmersus, ūs, m. [emergo], a coming out, coming forth, an appearing, emerging (not ante-Aug.): serpentium, Plin. 22, 22, 46, § 95: fluminis, id. 9, 22, 38, § 75: stellae, id. 18, 25, 58, § 218; Col. 7, 3, 24: hostium, Vitr. 10, 22.