What is Publisher?

Legal Definition
One who does by himself or his agents make a thing publicly known; one engaged in the circulation of books, pamphlets, and other papers.

2. The publisher of a libel is responsible as if he were the author of it, and it is immaterial whether he has any knowledge of its contents or not; 9 Co. 59; Hawk. P. C. c. 73, 10; 4 Mason, 115; and it is no justification to him that the name of the author accompanies the libel. 10 John, 447; 2 Moo. & R. 312.

3. When the publication is made by writing or printing, if the matter be libelous, the publisher may be indicted for a misdemeanor, provided it was made by his direction or consent, but if he was the owner of a newspaper merely, and the publication was made by his servants or agents, without any consent or knowledge on his part, he will not be liable to a criminal prosecution. In either case he will be liable to an action for damages sustained by the party aggrieved. 7 John. 260.

4. In order to render the publisher amenable to the law, the publication must be maliciously made, but malice will be presumed if the matter be libelous. This presumption, however, will be rebutted, if the publication be made for some lawful purpose, as, drawing up a bill of indictment, in which the libelous words are embodied, for the purpose of prosecuting the libeler; or if it evidently appear the publisher did not, at the time of publication, know that the matter was libelous as, when a person reads a libel presence of others, without beforehand knowing it to be such. 9 Co. 59. See Libel; Libeler; Publication.
-- Bouviers Law Dictionary
Legal Definition
One whose business is the manufacture, promulgation, and sale of books, pamphlets, magazines, newspapers or other literary productions,
-- Black's Law Dictionary
Legal Definition
One who makes anything known.
-- Ballentine's Law Dictionary