The paper gives a special construction of those words of length $n$ over any alphabet $\mathcal A=\{\alpha_1,\alpha_2,\dots,\alpha_m\}$ in which the subword $a\underbrace{b\dots b}_{k-1}a$ is forbidden for some natural number $k$ where the letters $a$ and $b$ are different and fixed from the alphabet $\mathcal A$. This construction gives the number of all these words. The number of such words is counted in two different ways, which gives some new combination identities.