- To mix two different frequencies in a nonlinear device, to produce two other frequencies. One frequency is the sum of the frequencies, while the other is their difference.
- To mix two different frequencies in a nonlinear device. Also, the output of such a mixture, which is called heterodyne frequency.
- verb to combine two signals of different frequencies to produce two new frequencies, one equal to the sum of and one equal to the difference between the original two signals