serio
From LSJ
ἐν δὲ μηνὸς πρῶτον τύχεν ἆμαρ → it chanced to be on the first of the month, that day fell on the first of the month
Latin > English
serio ADV :: seriously, in earnest
Latin > English (Lewis & Short)
sērĭō: adv., v. serius.
Latin > French (Gaffiot 2016)
sērĭō,¹¹ sérieusement : Pl. Amph. 906 ; Ter. Haut. 541 ; Liv. 7, 41, 3 ; Plin. Min. Ep. 2, 20, 10.
Latin > German (Georges)
sēriō, Adv., s. 1. sērius, a, um.