The process or act of making the membrane potential of a cell more negative
Hyperpolarization is a term that is used when referring to a process or act resulting in the membrane potential of a cell more negative than it typically is. Polarization is a condition wherein there are positive and negative electrical charges across the plasma membrane. The membrane potential of a cell, specifically neuron, is negative relative to its surroundings. The cell is able to maintain a relatively negative electrical charge due to the presence of more negative ions (e.g. Cl–) inside the cell. Typically, a neuron would have a resting potential of approximately -70 mV.1 In hyperpolarization, the membrane potential becomes more negative. This happens when there is an efflux of cations (i.e. K+ ions) through the K+) channels embedded in the plasma membrane. Another mechanism is by an influx of anions (i.e. Cl– ions) through the Cl–) channels.
Word origin: Greek hypér (over, above) + polarization
1 Polarization. Source: ://www.indiana.edu/~p1013447/dictionary/polarize.htm LINK