Disambiguating definitions specify a sense in which a word or phrase is or might be being used by a particular speaker on a particular occasion. (“When I said that the banks were collapsing, I meant river banks, not financial institu- tions.”) Disambiguating definitions can tell us which dictionary definition ac- tually is intended in a particular context, or they can distinguish several meanings that might be intended. They can also be used to remove syntactic ambiguity or amphiboly. (“When I said that all of my friends are not students, I meant that not all of them are students, not that none of them are students.”)
Whether the ambiguity is semantic or syntactic, the goal of a disam- biguating definition is to capture what the speaker intended, so such defini- tions can be justified by asking the speaker what he or she meant. This is a different question than asking what a word means. Whereas dictionary defi- nitions say what words mean or how they are used by most speakers of the language, a disambiguating definition focuses on a particular speaker and specifies which meaning that speaker intended on a particular occasion.
Such disambiguating definitions can be used in response to arguments that seem to commit the fallacy of equivocation. A critic can use disambiguating definitions to distinguish possible meanings and then ask, “Did you mean this or that?” The person who gave the argument can answer by picking one of these alternatives or by providing another disambiguating definition to spec- ify what was meant. Speakers are sometimes not sure which meaning they intended, and then the critic needs to show that the argument cannot work if a single disambiguating definition is followed throughout. Whether one sides with the arguer or the critic, arguments that use terms ambiguously cannot be evaluated thoroughly without the help of disambiguating definitions.