 In the second kind of definition—call it a heterogenous definition—the defined term and the definiendum belong to different logical categories. So, for example, a general term (e.g., ‘man’) may be defined using a sentential definiendum (e.g., ‘\(x\) is a man’). For another example, a singular term (e.g., ‘1’) may be defined using a predicate (e.g., ‘is identical to 1’). Heterogeneous definitions are far more common than homogenous ones. In familiar first-order languages, for instance, it is pointless to define, say, a one-place predicate \(G\) by a homogeneous definition. These languages have no resources for forming compound predicates; hence, the definiens of a homogeneous definition of \(G\) is bound to be atomic. In a heterogeneous definition, however, the definiens can easily be complex; for example,