In law, a renunciation, repudiation, or disavowal of rights, duties, or liabilities by words or conduct. Specifically:

(1) In actions involving real estate, a renunciation by a party of his character as tenant of one of the other parties to the action. Where a tenant sets up a claim of title in himself, superior to that of his landlord, or alleges that the one of whom he nominally holds possession is not the owner, or has not sufficient interest in the property to execute a valid lease, and refuses to recognize him as his landlord, it is said to be a disclaimer, and even if not sustained by the proof, works a forfeiture of the lease. A mere verbal refusal to recognize the lessor as landlord is not considered sufficient; it must be made where it will become a matter of record, as in a proceeding involving the rights of the landlord in the property.

(2) The act by which a person refuses to accept an estate which is devised or conveyed to him. This is usually accomplished by a deed, or other writing, and in order to be recognized without making application to the court, should be made before the devisee or grantee has in any way, by words or acts, shown assent to the devise or conveyance. It most frequently occurs where property is conveyed to one as trustee for another, and he does not care to assume the duties and responsibilities of the trust.

(3) In equity pleading, a written statement by the defendant disavowing or renouncing any interest in, or claim to, the matters set forth In the complainant's bill. It is a formal mode of defense, and entitles the defendant to a hearing on the question as to whether he has any interest or connection with the matters in controversy, and if he succeeds in establishing that he has not, he is entitled to an order striking out his name as party defendant. It does not deny any of the material allegations of the bill and should not be used where facts are alleged which, if not controverter, would show a liability on the part of the defendant. Usually, therefore, it accompanies an answer, and the two pleadings are considered together. See PLEADING.

(4) In patent law, a properly attested writing stating that the one who executes it is a patentee of a certain invention, and that he has discovered since filing his claim that he was not the first inventor of and therefore wishes to eliminate from his claim a part of the thing which he originally included, through mistake or inadvertence, in the specifications, or statement of the nature and object of his invention. This should be attested by witnesses and filed and recorded in the Patent Office, and it is then considered as a part of the original specifications. The part which he seeks to retain must be clearly separable and distinguishable from the part eliminated, and still be a patentable invention. Fraud or deception in making his original applications will prevent a patentee from taking advantage of this rule.