 Let \(\bK\) be a class of algebras in an algebraic language with a constant term for \(\bK\), i.e., a formula \(\phi(p_1 , \ldots ,p_n)\) such that for every algebra \(\bA\in \bK\) and elements \(a_1 , \ldots ,a_n, b_1, \ldots, b_n\) of \(\bA\), \(\phi^{\bA }[a_1 , \ldots ,a_n] = \phi^{\bA }[b_1 , \ldots ,b_n]\), that is, in every algebra in \(\bK\), \(\phi\) takes the same value whatever is the way we interpret the variable in \(\phi\) on \(\bA\). We denote this value by \(\phi^{\bA}\). Thus \(\phi\) acts as a constant (relative to the algebras in \(\bK\)) and \(\phi^{\bA}\) (for \(\bA\in \bK\)) can be taken as a designated element.