PCM, short for Pulse Code Modulation, can be referred to as digital audio, and there are several synonyms that can be used to describe it. Firstly, it can be called quantization, as it involves the process of quantizing analog signals into digital form. It is also sometimes given the name pulse modulation, as it involves the use of pulses to encode information. Another synonym for PCM is digital signal processing, as it involves processing digital signals to reproduce analog signals. Lastly, it can also be described as delta modulation, as it utilizes the principle of delta-sigma modulation for encoding analog signals. Regardless of the synonym used to describe it, PCM is an essential technology for modern digital audio.