The term “demurrer” refers to a pleading that is generally filed by a defendant in response to a complaint. A demurrer states that, although the facts alleged in the complaint may be true, they are not sufficient for the plaintiff to state a claim for relief and for the defendant to frame an answer.

In most jurisdictions, a demurrer is now called a “motion to dismiss.” However, the term demurrer is still used in a few jurisdictions such as California, Nebraska and Pennsylvania.

In pleading. The formal mode of disputing the sufficiency in law of the pleading of the other side. In effect it is an allegation that, even if the facts as stated in the pleading to which objection is taken be true, yet their legal consequences are not such as to put the demurring party to the necessity of answering them or proceeding further with the cause.

An objection made by one party to his opponent’s pleading, alleging that he ought not to answer it, for some defect in law.

In the pleading. It admits the facts, and refers the law arising thereon to the court. It imports that the objecting party will not proceed, but will wait the judgment of the court whether he is bound so to do.

In Equity. An allegation of a defendant, which, admitting the matters of fact alleged by the bill to be true, shows that as they are therein set forth they are insufficient for the plaintiff to proceed upon or to oblige the defendant to answer; or that, for some reason apparent on the face of the bill, or on account of the omission of some matter which ought to lie contained therein, or for want of some circumstances which ought to be attendant thereon, the defendant ought not to be compelled to answer to the whole bill, or to some certain part thereof.

Classification and varieties. A general demurrer is a demurrer framed in general terms, without showing specifically the nature of the objection, and which is usually resorted to where the objection is to matter of substance.

A special demurrer is one which excepts to the sufficiency of the pleadings on the opposite side, and shows specifically the nature of the objection, and the particular ground of the objection.

Source: Black’s Law Dictionary (2d ed.) (citations omitted).

DEMURRER (from Fr. demeurer, to delay, Lat. morari), in English law, an objection taken to the sufficiency, in point of law, of the pleading or written statement of the other side. In equity pleading a demurrer lay only against the bill, and not against the answer; at common law any part of the pleading could be demurred to. On the passing of the Judicature Act of 1875 the procedure with respect to demurrers in civil cases was amended, and, subsequently, by the Rules of the Supreme Court, Order XXV. demurrers were abolished and a more summary process for getting rid of pleadings which showed no reasonable cause of action or defence was adopted, called proceedings in lieu of demurrer. Demurrer in criminal cases still exists, but is now seldom resorted to. Demurrers are still in constant use in the United States. See Answer; Pleading.

Source:  Encyclopedia Britannica 11th Edition (1910-1911).