An abbreviation for: 1) Voltage Control Oscillator (an oscillator that generates an AC control voltage, usually a low-frequency oscillator putting out a signals between .1 Hz and 10 Hz). 2) Voltage Controlled Oscillator (an oscillator that changes its frequency according to a control voltage feed to its control input).
Found on http://www.encyclo.co.uk/local/20447
Voltage-controlled oscillator. An oscillator whose frequency can be changed by altering the amount of voltage being sent to its control input. Found on http://www.encyclo.co.uk/local/22285