1. Referring to a person who is influenced or acted upon without acting in return; offering no opposition or resistance: A passive behavior or conduct can also be described as receiving or enduring without resistance, being submissive, unassertive, or compliant.
2. In aviation, pertaining to a conveyance or thing that does not power itself: A passive flight, like gliding and soaring, or a balloon are just two examples of such passive airborne vehicles or objects.