Insubordination is the act — or the habit — of refusing to obey a person who has more authority than you. It is the noun that sits next to insubordinate. At work or in the army it names the offence: you were given an order, and you did not follow it. A report might say someone was dismissed for insubordination. Though actually, in everyday talk people more often say ‘he wouldn't listen’ or ‘she talked back’. Insubordination sounds like a rule book, a hearing, or a written warning. It is also not the same as disagreement. You can think a plan is foolish and still carry it out. Insubordination is when you will not carry it out. The word is countable in the sense of ‘an act of insubordination’, but you will often meet it as a mass noun, like a crime with a name.