Anything with two poles or opposites can be considered bipolar. The yin and yang symbol (black and white or male and female) is an example of bipolar or opposing natures. However, this term is used most often to describe bipolar disorder, also known as manic-depressive illness, which is when you experience very high highs and very low lows with your emotions. The negative and positive charge on a neuron or a transistor can also be called bipolar.