Defamation is widely defined under Section 499 of IPC: “Whoever, by words either spoken or intended to be read, or by signs or by visible representations, makes or publishes any imputation concerning any person intending to harm, or knowing or having reason to believe that such imputation will harm, the reputation of such person, is said, except in the cases hereinafter excepted, to defame that person.”
So, the definition is quite wide and may cover the situation described by you, depending on the facts of your case. As rightly pointed by another member, offence of defamation may be made out even without quashing of the case, though of course, burden lies on you to prove the ingredients of the defamation case. Quashing of the case may be on merits or on technical grounds. However, please remember that in the situation described by you, two Exceptions mentioned in Section 499 IPC become relevant, namely the Eighth Exception and the Ninth Exception, which are quoted below:
“Eighth Exception.—Accusation preferred in good faith to authorised person.—It is not defamation to prefer in good faith an accusation against any person to any of those who have lawful authority over that person with respect to the subject-matter of accusation.”
“Ninth Exception.—Imputation made in good faith by person for protection of his or other’s interests.—It is not defamation to make an imputation on the character of another provided that the imputation be made in good faith for the protection of the interest of the person making it, or of any other person, or for the public good.”
Therefore, if you intend to file a defamation case, you may have to prove that the filing of the FIR was NOT covered under the above two exceptions, i.e., for example, you may have to show that the allegations / accusations mentioned in the FIR were NOT made in good faith. If the allegations made were completely false, it may be of help in the defamation case.
Ultimately, the detailed facts of your case will decide the fate of the defamation case on the broad principles of law outlined above.