A quick definition of prior publication:

Prior publication refers to when information about an invention is made available to the public before a patent application is filed. If this happens more than a year before the application is filed, the patent cannot be granted. Publication can also refer to the act of making a work available to the public, either through distribution or announcement. Before the Copyright Act of 1976, publication was an important factor in determining state and federal protection for a work. There are different types of publication, including limited publication (distribution to a selected group for a limited purpose), general publication (distribution to the public), and private publication (limited publication). In the context of defamation, publication refers to the communication of defamatory words to someone other than the person defamed. Finally, in the context of wills, publication refers to the formal declaration made by a testator when signing the will that it is their will.