x patent
X-patent. Patents. An early U.S. patent, granted before the numbering system set up in the Patent Act of 1836 and so named because an X was added to the numbers of existing patents to avoid duplicate numbers.
X-patent. Patents. An early U.S. patent, granted before the numbering system set up in the Patent Act of 1836 and so named because an X was added to the numbers of existing patents to avoid duplicate numbers.