rĕbellĭum — Lewis & Short
rĕbellĭum, ii, n.id.,
I a renewal of war, revolt, rebellion (a collat. form for rebellio, like consortium for consortio, contagium for contagio, etc.):
qui pacatos ad rebellium incitasset,Liv. 42, 21, 3 Gronov. (dub.; Weissenb. rebellandum).