Passive is the opposite of active. In English class, you might be advised to avoid the passive voice. In chemistry, a passive substance doesn't react. Passive resistance is a way to protest peacefully.
When you're passive, you don't participate much and you're not very emotional. In chemistry, passive means to be "unreactive except under special or extreme conditions; inert." Gandhi used the term passive resistance in the mid-twentieth century to describe the nonviolent approach Indians should use in their quest to become an independent nation.