Latin: Let him beware. A formal notice or warning given by a party interested to a court, judge, or ministerial officer against the performance of certain acts within his power and jurisdiction. This process may be used in the proper courts to prevent (temporarily or provisionally) the proving of a will or the grant of administration, or to arrest the enrollment of a decree in chancery when the party intends to take an appeal, to prevent the grant of letters patent, etc. It is also used, in the American practice, as a kind of equitable process, to stay the granting of a patent for lands. Wilson v. TJaston, 92 Pa. 207; Slocum v. Grandin, 38 N. J. Eq. 485; Ex parte Grafts, 28 S. O. 281, 5 S. E. 718; In re Miller’s Estate, 166 Pa. 97, 31 Atl. 58. In patent law. A caveat is a formal written notice given to the officers of the patent office, requiring them to refuse letters patent on a particular invention or device to any other person, until the party filing the caveat (called the “caveator”) shall have an opportunity to establish his claim to priority of invention.