When you say that someone's fingertip is touching the edge of the pool, you are saying that the person is very close to the edge of the pool.
Corns are small, hard bumps that you can get on your feet. They are usually caused by walking on hard surfaces for a long period of time.
Gluons are tiny particles that are responsible for the strong nuclear force. They are also responsible for the binding of protons and neutrons together in atoms.
Quarks are the smallest particles that make up matter. They are also the building blocks of atoms.
To compact something is to make it smaller and more dense. When you compacted the soil, you made it more dense and easier to plant crops in.
The orbitals are the energy levels that are associated with the electron. The orbitals are divided into two types, s and p orbitals.
Thingies refers to any small, random objects that you might find around the house. When you're cleaning, you might find thingies on the floor and on the counter.
To mindboggling is to be completely amazed or bewildered by something. When you mindboggle someone, you make them feel very surprised and confused.