To find the domain of the function \( f(x) = \log(14 - x) \), we need to determine the values of \( x \) for which the argument of the logarithm is positive. Specifically, we require:
\[ 14 - x > 0 \]
Solving this inequality, we add \( x \) to both sides:
\[ 14 > x \]
or equivalently,
\[ x < 14 \]
Additionally, there is no restriction on how low \( x \) can go, so we have:
\[ x \in (-\infty, 14) \]
Thus, the domain of \( f(x) \) in interval notation is:
\[ \boxed{(-\infty, 14)} \]