Uncooperative means refusing to work with others or help when you're supposed to. An uncooperative student might ignore their group during a team project, leaving everyone else to do the work. An uncooperative witness in court might refuse to answer questions, making it hard to figure out what really happened.

The word describes someone who won't go along with reasonable requests or join in shared efforts. If your sister is being uncooperative during family chores, she might drag her feet, complain constantly, or simply refuse to help. An uncooperative dog won't sit or come when called, no matter how many treats you offer.

Being uncooperative is different from simply disagreeing or having a better idea. When you suggest a different approach to solving a math problem, that's thinking independently. But when you refuse to participate at all or deliberately make things harder for everyone, that's being uncooperative.

People become uncooperative for different reasons: sometimes they're angry, sometimes they feel the task is unfair, and sometimes they just don't want to make an effort. Whatever the reason, uncooperative behavior makes everything take longer and frustrates the people trying to accomplish something together.