Dual SideBand - Suppressed Carrier. A form of amplitude modulation that essentially involves multiplying the signal by a cosine signal (a sine wave, the math comes out nicer if you use cosine for it though the waves are effectively identical).
Or, in other symbols, given an input signal G(x), the output signal H(x) is G(x)*cos(f*t), where f is the frequency in radians.
This signal is referred to as Dual SideBand - Suppressed Carrier because of its Fourier transform, which looks like two half-height Fourier transforms of the original signal, one centered at the frequency of the carrier wave (the sine wave) and one at the negative of the frequency.
This modulation scheme is not commonly used for wireless signals because it requires a coherent demodulator, that is, the receiving radio needs a frequency-matched oscillator.
Compare Standard AM, single sideband, and QAM.