argumentative
Tending to argue or disagree a lot, often unnecessarily.
Argumentative means tending to argue or disagree, often over small things or for no good reason. An argumentative person seems always ready for a debate, even when one isn't needed. If your friend becomes argumentative every time you suggest which game to play, they're turning every choice into a fight and making their preference into a battle.
The word can describe both people and their behavior. An argumentative classmate might challenge everything the teacher says, not because they're curious but because they enjoy disagreeing. An argumentative tone in writing sounds like the author is spoiling for a fight rather than explaining ideas calmly.
Being argumentative is different from having strong opinions or standing up for yourself. It's about the manner and frequency of disagreement. Someone who argues against genuine unfairness is being brave. Someone who argues about whether lunch should start at 12:00 or 12:05 is being argumentative. The difference lies in whether you're disagreeing because something truly matters or because you've developed a habit of contradiction.
Interestingly, the word has a more positive meaning in formal writing. An argumentative essay isn't picking fights: it presents a clear position with supporting evidence and reasoning, which is actually a valuable skill in school and life.