Lewis Short
(adj.adv.) : 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.
Charlton T. Lewis, Charles Short, A Latin Dictionary