Formal noun for refusal to obey authority, rules, or instructions. Often used in legal, military, or parental contexts.
His disobedience became a problem.
In the military, insubordination is severely punished.
不服従 is a near-synonym, but 不従順 is slightly more common and often implies a character trait rather than a single act.
Compound of 不 (not) + 従順 (obedient). The word follows standard Sino-Japanese word formation.