The build-up of a static charge, typically through a physical means, that creates a voltage differential between objects. This voltage differential usually results in a large discharge when the objects come together, either causing pain or destruction. A tricky part of that static discharge is that sometimes the discharge isn’t even noticeable but it can still cause damage to electronics.
Static electricity is accumulation of charge. Electric charges not in motion.
Grob’s Basic Electronics, 11th Edition by Mitchel E. Schultz
Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it is able to move away by means of an electric current or electrical discharge. Static electricity is named in contrast with current electricity, which flows through wires or other conductors and transmits energy.
A static electric charge can be created whenever two surfaces contact and separate, and at least one of the surfaces has a high resistance to electric current (and is therefore an electrical insulator). The effects of static electricity are familiar to most people because people can feel, hear, and even see the spark as the excess charge is neutralized when brought close to a large electrical conductor (for example, a path to ground), or a region with an excess charge of the opposite polarity (positive or negative). The familiar phenomenon of a static shock – more specifically, an electrostatic discharge – is caused by the neutralization of charge.