Lewis Short
(verb) : dē-cōlo, āvi (
* Old fut. perf. decolassit = decolaverit, Plaut. Cas. 2, 4, 28), 1, colum; lit., to trickle from or through; hence trop., to come to naught, to fail (ante-class.): si spes decolabit,Plaut. Gapt. 3, 1, 37; cf. id. Casin. 2, 4, 28: quorum si alterutrum decolat,Varr. R. R. 1, 28.
Charlton T. Lewis, Charles Short, A Latin Dictionary