Having, or presupposing, a use of terms that relates not to the extension (that is, the individual things that actually happen to fall under these terms in this world) but determines what could or could not fall under the term (in for example any possible world). e.g. The extension of "having a heart" and "having a kidney" is the same in this world because in fact all creatures that have one have the other. But the intension is not the same because a creature with one feature might not have the other. See extension.