thumb|A trephine with a center pin can be seen on the left. thumb|right|Dr. John Clarke [[trepanning a skull, ca. 1664, in one of the earliest American portraits. Clarke has a trephine in his right hand. The painting is in Harvard Medical School.]]
thumb|A trephine with a center pin can be seen on the left. thumb|right|Dr. John Clarke [[trepanning a skull, ca. 1664, in one of the earliest American portraits. Clarke has a trephine in his right hand. The painting is in Harvard Medical School.]]
A trephine (; from Greek τρύπανον, trypanon 'instrument for boring') is a surgical instrument with a cylindrical blade. It can be of one of several dimensions and designs depending on what it is meant to be used for. A trephine may be specially designed for obtaining a cylindrically shaped core of bone that can be used for tests and bone studies, cutting holes in bones (e.g., the skull), or cutting out a round piece of the cornea for eye surgery.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).