bipolar

Concise Oxford English Dictionary © 2008 Oxford University Press:
bipolar/bʌɪˈpəʊlə(r)/

▶adjective

• 1 having or relating to two poles or extremities.

  ■ (of a plant or animal species) of or occurring in both polar regions.

• 2 (of psychiatric illness) characterized by both manic and depressive episodes, or manic ones only.

  ■ (of a person) suffering from bipolar disorder.

• 3 (of a nerve cell) having two axons, one either side of the cell body.

• 4 Electronics (of a transistor or other device) using both positive and negative charge carriers.

– derivatives
bipolarity noun.