Intervallum | Webster's Dictionary of the English Language

intervallum
inter-vallum, i, n., prop., the open space within the mound or breastwork of a camp, the space betwe...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
intervallum
inter-vāllum ī, n —Prop., the space between palisades, an intermediate space, interval, distance: p...

An Elementary Latin Dictionary