In CycL, denotational terms, represented in the Cyc Knowledge Base by #$CycLDenotationalTerm, are terms that are not CycL sentences, and thus are either atomic terms (such as constants or variables) or non-atomic terms (also known as “NAT”s). Denotational terms are so-called, not because they all have denotations (not all of them do), but because they are in a certain sense the right kind of term for having a denotation. That is, each denotational term — if it is semantically well-formed and closed (i.e. contains no free variables) — might denote something in the universe of discourse.
An Euler diagram of terms in Cyc.