I got detention because a teacher said I was being contumacious. What's that?

Do you have a bit of a stubborn streak or rebel in you? Being contumacious means you're obstinately resisting authority or being disobedient. In Great Expectations, Pip's sister complains to her friend, Mrs. Hubble, about him:
"He was a world of trouble to you, ma'am," said Mrs. Hubble, commiserating my sister.

"Trouble?" echoed my sister; "trouble?" and then entered on a fearful catalogue of all the illnesses I had been guilty of, and all the acts of sleeplessness I had committed, and all the high places I had tumbled from, and all the low places I had tumbled into, and all the injuries I had done myself, and all the times she had wished me in my grave, and I had contumaciously refused to go there.