infantĭlis, e, adj. [infans], of or belonging to infants or little children (post-class.): vestis, Dig. 34, 2, 25: blandimenta, Just. 17, 3, 20: uterus, little, young, App. M. 5, p. 164, 12.
Hence, adv.: infantĭlĭter, like a child, Hier. Orig. in Jer. Hom. 1, p. 750.