An Etymological Dictionary of Astronomy and Astrophysics
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1) Physics: The condition, in a system, of having opposite characteristics at different points, especially positive or negative with respect to electric charge or magnetic properties.
2) Chemistry: A property of a molecule caused by unsymmetrical charge distribution.

From → polar + → -ity.

The time during which the Earth's magnetic field was of a single polarity; an interval of time between reversals of Earth's magnetic field.

→ polarity; → epoch.

A specific event in the history of Earth's magnetic field. Usually used in reference to a specific → polarity reversal.

→ polarity; → event.

1) A change in the → polarity of Earth's magnetic field in which the north magnetic pole becomes the south magnetic pole and vice versa. Also known as geomagnetic reversal or magnetic reversal. Earth's magnetic field has reversed many times in the past and the time intervals between these changes are known as → polarity epochs.
2) The change in the polarity of the → solar magnetic field with the ending of each → solar activity cycle so that the North magnetic pole becomes the South and vice versa.

→ polarity; → reversal.