involved
Taking an active part in something.
To be involved means to be part of something or connected to it in an active way. When you're involved in the school play, you might be acting, building sets, or helping with costumes. You're actively participating in making the production happen. When a teacher says everyone needs to get involved in the group project, she means everyone should contribute and participate, taking an active role rather than sitting quietly while others do the work.
The word suggests more than casual connection. You might hear about a science experiment at dinner, but you're only involved if you're actually conducting it. A detective becomes involved in a case when she starts investigating it. Your parents are deeply involved in your life because they care about and participate in what happens to you.
Something can also be involved without people: when a car accident involves three vehicles, all three are part of what happened. When a recipe involves multiple steps, those steps are necessary parts of making the dish.
Involved can also mean complicated or intricate. An involved math problem has many steps and requires careful attention. When someone gives you an involved explanation, they're including so many details and connections that it can be hard to follow quickly.