Origin: 1400–50; late ME < ML
rebelliōsus, equiv. to L
rebelli(
ō)
rebellion +
-ōsus -ous 
Related forms: re⋅bel⋅lious⋅ly, adverb
re⋅bel⋅lious⋅ness, noun
Synonyms:
1. defiant, insurgent, mutinous, seditious, rebel, refractory, disobedient, contumacious.