Definition (Codeword)

Given a fixed length or variable length code, a source alphabet $\mathcal{X}$, a codebook $\mathcal{C}$, and an encoder $f:\mathcal{X}^n\to\mathcal{C}^*$ where $\mathcal{C}^*$ is the set of all finite-length sequences over $\mathcal{C}$. A codeword for a symbol $x^n\in\mathcal{X}^n$ is the encoded source $n$-tuple $f(x^n)$.