Available Definitions:
1) subj. 3d pers. sing. - Let it stand; -- a word used by proof readers to signify that something once erased, or marked for omission, is to remain.
2) v. t. - To cause or direct to remain after having been marked for omission; to mark with the word stet, or with a series of dots below or beside the matter; as, the proof reader stetted a deled footnote.