bit width - Also known as bit depth, bit length, wordlength. Bit depth is the number of bits that an audio device is capable of using to express the quantization, or amplitude information in a sampled audio waveform. The size of the bit depth in digitized audio (sampling) directly effects the accuracy of this amplitude information, such that greater bit depth = greater dynamic range.
quantization error - When the analog amplitude being sampled falls between a quantization interval (each bit), the system can no longer resolve the amplitude of the input signal, and a quantization error occurs. This is most often spoke of in terms of the resolution below 1 bit, or the least significant bit.