Individual constant in the context of "Predicate (mathematical logic)"

In logic, a predicate is a non-logical symbol that represents a property or a relation, though, formally, does not need to represent anything at all. For instance, in the first-order formula ${\displaystyle P(a)}$, the symbol ${\displaystyle P}$ is a predicate that applies to the individual constant ${\displaystyle a}$ which evaluates to either true or false. Similarly, in the formula ${\displaystyle R(a,b)}$, the symbol ${\displaystyle R}$ is a predicate that applies to the individual constants ${\displaystyle a}$ and ${\displaystyle b}$. Predicates are considered a primitive notion of first-order, and higher-order logic and are therefore not defined in terms of other more basic concepts.

The term derives from the grammatical term "predicate", meaning a word or phrase that represents a property or relation.