The term 'Part of a Circle' can be described by two crossword solutions: ARC (3 letters) and SECTOR (6 letters). An ARC is a curved line that forms part of the circumference of a circle. It is usually measured in degrees, with a full circle being 360 degrees. A SECTOR is a region of a circle bounded by two radii and an ARC. It is also measured in degrees, with the area of the SECTOR being proportional to the angle of the ARC.