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.
When the threshold voltage is reached, which is typically at -55 mV, the ion channels open in order to allow positive charges to rush inside the cell. This is known as depolarization, which is the process of becoming positively charged. After a cell depolarizes, it will eventually reach a maximum positive charge.