levity

noun
  1. A manner lacking seriousness, often characterized by humor or frivolity, especially in situations that require seriousness. noun
    His attempt to introduce levity into the solemn proceedings was not well received.
    The teacher's levity during the lecture helped to engage the students.
  2. Lightness in weight or buoyancy, though this usage is now rare. noun
    The levity of the balloon allowed it to float effortlessly into the sky.
    The concept of levity in physics refers to an object's ability to rise or float in a fluid.