An air bubble is a pocket of air that is trapped in a liquid or solid. An EMBOLUS is a bubble of air or gas that can travel through the bloodstream and cause a blockage. A BLEB is a small bubble of air or gas that forms on the surface of a liquid. LEVEL is a term used to describe a surface that is even and flat. TOIL is a term used to describe hard work or labor. Together, these terms can be used to describe an air bubble, which is a pocket of air that is trapped in a liquid or solid, and can cause a blockage if it travels through the bloodstream.