A groove or furrow, especially one on the surface of the brain separating adjacent gyri. The central sulcus is a prominent landmark of the brain, separating the frontal and parietal lobes.
A groove or depression on the surface of an organ or tissue. The dentist noted a deep sulcus around the patient's tooth, indicating potential gum disease.
A set of parallel furrows and ridges on the surface of a planet or moon, identified as a distinct geological feature. Spacecraft images revealed bright icy sulci cutting across Europa’s crust.