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An electronics designation that refers to voltage from a power supply connected to the "collector" terminal of a bipolar transistor. In an NPN bipolar (BJT) transistor, it would be +Vcc, while in a PNP transistor, it would be -Vcc.
Double letters (cc) refer to power supply voltages. For example, Vee refers to the "emitter" voltage. In CMOS logic, Vss refers to the "source" voltage, and Vdd is the "drain" voltage.
Single letters refer to the voltage relative to ground; for example, Vc is the "collector" voltage relative to ground. Two different letters indicate the voltage between two terminals; for example: Vbe is the "base" to "emitter" voltage drop, while Vce is the "collector" to "emitter" voltage.