Aliasing

In analog-to-digital conversion, the misrepresentation of a continuous signal in a discrete waveform is called aliasing, and it occurs when the continuous signal contains frequency components that are higher than half the sampling rate (i.e. higher than the Nyquist frequency).

Comment
To avoid aliasing, the sampling rate must be increased to capture all the frequency components in the analog signal, or the frequencies above half the sampling rate must be filtered out.

Link
Utrecht Lexicon of Linguistics