1. A short straight cut made through the wall of a cavity or canal.
2. The contraction of an orifice down to a narrow slit; the so-called mitral buttonhole in extreme mitral stenosis.
The information shown above for buttonhole is provided by Stedman's.
* Stedman's, part of Lippincott Williams & Wilkins, provide a comprehensive line of health-science publications for healthcare professionals and medical students.