Lewis Short
jentācŭlum (noun N) : jento
* A breakfast, taken immediately after rising, by children, valetudinarians, etc. (whereas the prandium was not taken till towards noon): epulas interdum quadrifariam dispertiebat: in jentacula et prandia et cenas comissationesque,Suet. Vit. 13; Mart. 14, 233: me inferre Veneri vovi jam jentaculum,Plaut. Curc. 1, 1, 72.
Charlton T. Lewis, Charles Short, A Latin Dictionary