Theoretically, a recognized member of the modern state system possessing formal sovereignty and occupied by a people who see themselves as a single, united nation. Most nations and states aspire to parlance, nation-state is used as a synonym for country or state.
In biology, depolarization is a decrease in the absolute value of a cell's membrane potential. Thus, changes in membrane voltage in which the membrane potential becomes less positive or less negative are both depolarizations.
Nerve cells at rest have an electrical charge across their membranes: the outside of the cell is positively charged and the inside of the cell is negatively charged. Depolarization occurs when the nerve cell reverses these charges; to change them back to an at-rest state, the neuron sends another electrical signal. The entire process occurs when the cell allows specific ions to flow into and out of the cell.