A CycL sentence, represented in the Cyc Knowledge Base by #$CycLSentence, is a type of CycL formula that constitutes a syntactically well-formed sentence in the CycL language. Every CycL sentence consists of a CycL expression denoting an instance of #$TruthFunction (e.g. an instance of #$Predicate or #$SententialRelation) followed by one or more CycL terms, with the entire sequence enclosed in parentheses. For example, (isa Collection Thing) and (genls ?FOO SpatialThing) are both CycL sentences. Assertions are a notable type of CycL sentence.
An Euler diagram of terms in Cyc.