Refers to the requirement for a patent that an invention be new. Thus for example under United States law (35 U.S.C. §102) a patent may not be granted if the same device if created by a third party was described or in use before its priority date, or if it was described in a publication by the inventor more than one year prior to the application date for the patent.
In U.S. law novelty is a different issue from obviousness —an invention is only non-novel if it was wholly and essentially identically described (i.e., all claim limitations met) in a single publication or found in an item of prior art, whereas an invention is obvious under 35 U.S.C. §103 if the invention would have been obvious to someone of ordinary skill in the art, especially someone who had knowledge of the prior art, even if that person needs to combine items of prior art. In other words, novelty asks if someone has actually made it before, obviousness asks if a reasonably skilled and educated person could have made it before.
Absolute novelty is the terms used to describe a novelty requirement where any prior art before the filing date, anywhere in the world precludes grant of a patent, i.e., there is no grace period. European Patent law is considered as applying absolute novelty.